Install aftermarket expression functions (#11472)

* [ios, macos] Introduced more ergonomic expression concatenation syntax

* [ios, macos] Fixed mgl_join:

* [ios, macos] Simplified expression document headings

* [ios, macos] Documented mgl_join:

* [ios, macos] Convert length operator to length: for strings

Only works for literal strings.

* [ios, macos] Implemented type conversion using CAST()

* [ios, macos] Aftermarket let expressions

* [ios, macos] Refactored aftermarket expression functions

Refactored the installation of aftermarket expression functions to use macros. It is no longer necessary to handwrite the type encoding of a function. Also added aftermarket functions for interpolating and stepping.

* [ios, macos] Updated documentation, tests, demo apps

* [ios, macos] Added generic expression function

* [ios, macos] Add MGL_MATCH function placeholder.

* [ios, macos] Add MGL_SWITCH expression operator.

* [ios, macos] Add mgl_coalesce: as expression function.

* [ios, macos] Update style documentation.

* [ios, macos] Add conventional custom function support.

* [ios, macos] Updated example code

* [ios, macos] Add mgl_coalesce conventional custom function support.

* [ios, macos] Add aftermarket function to 'has' operator.

* [ios, macos] Add documentation for lookup and feature operators.

* [ios, macos] Documented simple lookup

* [ios, macos] Renamed, reversed has expression

Renamed mgl_hasProperty:properties: to mgl_does:have: for better readability and consistency with the conventional mgl_has: function. Documented both forms of mgl_has:.

* [ios, macos] Restored OEM conditionals where available

This is the preferred syntax for simple conditionals on iOS 9 and above, because you can inline the predicate instead of wrapping it in a constant value expression, which means you can write a conditional in a single format string.

* [ios, macos] Update style docs.

Co-authored-by: Fabian Guerra <fabian.guerra@mapbox.com>

30 files changed, 990 insertions, 571 deletions

diff --git a/platform/darwin/docs/guides/For Style Authors.md.ejs b/platform/darwin/docs/guides/For Style Authors.md.ejs
index 2ba7757fdf..45cfa105b8 100644
--- a/platform/darwin/docs/guides/For Style Authors.md.ejs
+++ b/platform/darwin/docs/guides/For Style Authors.md.ejs
@@ -321,6 +321,11 @@ iOS.
 <% } -%>
 ### Expression operators
 
+Many expression operators defined in the style specification have corresponding
+symbols to be used with the `+[NSExpression expressionWithFormat:]`,
+`+[NSExpression expressionForFunction:arguments:]`, or
+`+[NSExpression expressionForFunction:selectorName:arguments:]` method:
+
 In style specification | Method, function, or predicate type | Format string syntax
 -----------------------|-------------------------------------|---------------------
 `array`                | |
@@ -330,15 +335,15 @@ In style specification | Method, function, or predicate type | Format string syn
 `string`               | |
 `to-boolean`           | `boolValue` |
 `to-color`             | |
-`to-number`            | `mgl_numberWithFallbackValues:` |
-`to-string`            | `stringValue` |
+`to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
+`to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
-`geometry-type`        | |
-`id`                   | |
-`properties`           | |
-`at`                   | |
+`geometry-type`        | |`$mgl_geometryType`
+`id`                   | |`$mgl_featureIdentifier`
+`properties`           | |`$mgl_featureProperties`
+`at`                   | `objectFrom:withIndex:` | `array[n]`
 `get`                  | `+[NSExpression expressionForKeyPath:]` | Key path
-`has`                  | |
+`has`                  | `mgl_does:have:` | `mgl_does:have:(self, 'key')`
 `length`               | `count:` | `count({1, 2, 2, 3, 4, 7, 9})`
 `!`                    | `NSNotPredicateType` | `NOT (p0 OR … OR pn)`
 `!=`                   | `NSNotEqualToPredicateOperatorType` | `key != value`
@@ -349,14 +354,14 @@ In style specification | Method, function, or predicate type | Format string syn
 `>=`                   | `NSGreaterThanOrEqualToPredicateOperatorType` | `key >= value`
 `all`                  | `NSAndPredicateType` | `p0 AND … AND pn`
 `any`                  | `NSOrPredicateType` | `p0 OR … OR pn`
-`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` | `TERNARY(condition, trueExpression, falseExpression)`
-`coalesce`             | |
-`match`                | |
-`interpolate`          | `mgl_interpolateWithCurveType:parameters:stops:` |
-`step`                 | `mgl_stepWithMinimum:stops:` |
-`let`                  | `mgl_expressionWithContext:` |
+`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` or `MGL_IF` | `TERNARY(1 = 2, YES, NO)` or `MGL_IF(1 = 2, YES, 2 = 2, YES, NO)`
+`coalesce`             | `mgl_coalesce:` | `mgl_coalesce({x, y, z})`
+`match`                | `MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')`
+`interpolate`          | `mgl_interpolate:withCurveType:parameters:stops:` |
+`step`                 | `mgl_step:withMinimum:stops:` |
+`let`                  | `mgl_expressionWithContext:` | `MGL_LET('ios', 11, 'macos', 10.13, $ios + $macos)`
 `var`                  | `+[NSExpression expressionForVariable:]` | `$variable`
-`concat`               | `stringByAppendingString:` |
+`concat`               | `mgl_join:` | `mgl_join({'Old', ' ', 'MacDonald'})`
 `downcase`             | `lowercase:` | `lowercase('DOWNTOWN')`
 `upcase`               | `uppercase:` | `uppercase('Elysian Fields')`
 <% if (macOS) { -%>
@@ -391,6 +396,9 @@ In style specification | Method, function, or predicate type | Format string syn
 `zoom`                 | | `$zoom`
 `heatmap-density`      | | `$heatmapDensity`
 
+For operators that have no corresponding `NSExpression` symbol, use the
+`MGL_FUNCTION()` format string syntax.
+
 ## Filtering sources
 
 You can filter a shape or vector source by setting the
diff --git a/platform/darwin/docs/guides/Predicates and Expressions.md b/platform/darwin/docs/guides/Predicates and Expressions.md
index 19d98fd4c1..4abdcff492 100644
--- a/platform/darwin/docs/guides/Predicates and Expressions.md
+++ b/platform/darwin/docs/guides/Predicates and Expressions.md
@@ -123,9 +123,7 @@ style attributes and also `hyphen-minus` and `tag:subtag`. However, you must use
 
 ## Using expressions to configure layout and paint attributes
 
-### Functions
-
-#### Key paths
+### Key paths
 
 A key path expression refers to an attribute of the `MGLFeature` object being
 evaluated for display. For example, if a polygon’s `MGLFeature.attributes`
@@ -133,7 +131,7 @@ dictionary contains the `floorCount` key, then the key path `floorCount` refers
 to the value of the `floorCount` attribute when evaluating that particular
 polygon.
 
-#### Predefined functions
+### Predefined functions
 
 Of the
 [functions predefined by the `+[NSExpression expressionForFunction:arguments:]` method](https://developer.apple.com/documentation/foundation/nsexpression/1413747-init#discussion),
@@ -163,6 +161,8 @@ Initializer parameter | Format string syntax
 `uppercase:`          | `uppercase('Elysian Fields')`
 `lowercase:`          | `lowercase('DOWNTOWN')`
 `noindex:`            | `noindex(0 + 2 + c)`
+`length:`             | `length('Wapakoneta')`
+`castObject:toType:`  | `CAST(ele, 'NSString')`<br>`CAST(ele, 'NSNumber')`
 
 The following predefined functions are not supported:
 
@@ -182,13 +182,28 @@ Initializer parameter | Format string syntax
 `onesComplement:`     | `onesComplement(255)`
 `distanceToLocation:fromLocation:` | `distanceToLocation:fromLocation:(there, here)`
 
-#### Mapbox-specific functions
+### Mapbox-specific functions
 
 For compatibility with the Mapbox Style Specification, the following functions
-are defined by this SDK for use with style layers. Because these functions are
-not predefined by `NSExpression`, you must use the
+are defined by this SDK. When setting a style layer property, you can call these
+functions just like the predefined functions above, using either the
+`+[NSExpression expressionForFunction:arguments:]` method or a convenient format
+string syntax:
+
+Initializer parameter | Format string syntax | Description
+----------------------|----------------------|------------
+`mgl_does:have:` | `mgl_does:have:(SELF, 'key')` or `mgl_does:have:(%@, 'key')` | Returns a Boolean value indicating whether the dictionary has a value for the key or whether the evaluated object (`SELF`) has a value for the feature attribute. Compared to the `mgl_has:` custom function, that function’s target is instead passed in as the first argument to this function. Both functions are equivalent to the syntax `key != NIL` or `%@[key] != NIL` but can be used outside of a predicate.
+`mgl_interpolate:withCurveType:parameters:stops:` | `mgl_interpolate:withCurveType:parameters:stops:(x, 'linear', nil, %@)` | Produces continuous, smooth results by interpolating between pairs of input and output values (“stops”). Compared to the `mgl_interpolateWithCurveType:parameters:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
+`mgl_step:from:stops:` | `mgl_step:from:stops:(x, 11, %@)` | Produces discrete, stepped results by evaluating a piecewise-constant function defined by pairs of input and output values ("stops"). Compared to the `mgl_stepWithMinimum:stops:` custom function, the input expression (that function’s target) is instead passed in as the first argument to this function.
+`mgl_join:` | `mgl_join({'Old', 'MacDonald'})` | Returns the result of concatenating together all the elements of an array in order. Compared to the `stringByAppendingString:` custom function, this function takes only one argument, which is an aggregate expression containing the strings to concatenate.
+`mgl_coalesce:` | `mgl_coalesce({x, y, z})` | Returns the first non-`nil` value from an array of expressions.
+`MGL_LET` | `MGL_LET('age', uppercase('old'), 'name', uppercase('MacDonald'), mgl_join({$age, $name}))` | Any number of variable names interspersed with their assigned `NSExpression` values, followed by an `NSExpression` that may contain references to those variables. Compared to the `mgl_expressionWithContext:` custom function, this function takes the variable names and values inline before the expression that contains references to those variables.
+`MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')` | Evaluates the first expression and returns the value that matches the initial condition. After the first expression condition a pair of matching/return value should be added and a default value.
+`MGL_IF` | `MGL_IF(1 = 2, YES, 2 = 2, YES, NO)` | Returns the first value that meets the condition otherwise a default value. The expression conditions should be added in pairs of conditional/return value. Unlike `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` or the `TERNARY()` syntax, this function can accept multiple “if else” conditions and is supported on iOS 8._x_ and macOS 10.10._x_; however, each conditional passed into this function must be wrapped in a constant expression.
+
+The following custom functions are also available with the
 `+[NSExpression expressionForFunction:selectorName:arguments:]` method or the
-`FUNCTION()` format string syntax instead. 
+`FUNCTION()` format string syntax:
 
 <table>
 <thead>
@@ -207,6 +222,17 @@ not predefined by `NSExpression`, you must use the
    </td>
 </tr>
 <tr>
+   <td><code>mgl_has:</code></td>
+   <td>
+      An `NSExpression` that evaluates to an <code>NSDictionary</code> or the evaluated object (<code>SELF</code>).
+   </td>
+   <td>
+      An `NSExpression` that evaluates to an <code>NSString</code> representing the key to look up in the dictionary or the feature attribute to look up in the evaluated object (see <code>MGLFeature.attributes</code>).
+   </td>
+   <td>
+      `true` if the dictionary has a value for the key or if the evaluated object has a value for the feature attribute.
+   </td>
+<tr>
    <td><code>mgl_expressionWithContext:</code></td>
    <td>
       An `NSExpression` that may contain references to the variables defined in
@@ -366,6 +392,10 @@ classes, but you should not call them directly outside the context of an
 expression, because the result may differ from the evaluated expression’s result
 or may result in undefined behavior.
 
+The Mapbox Style Specification defines some operators for which no custom
+function is available. To use these operators in an `NSExpression`, call the
+`MGL_FUNCTION()` function with the same arguments that the operator expects.
+
 ### Variables
 
 The following variables are defined by this SDK for use with style layers:
@@ -404,11 +434,9 @@ of a [Mapbox-specific function](#mapbox-specific-functions) that takes an
 `NSDictionary` as an argument:
 
 ```objc
-[NSExpression expressionWithFormat:@"FUNCTION($floorCount + 1, 'mgl_expressionWithContext:', %@)",
- {@"floorCount": @2}];
+[NSExpression expressionWithFormat:@"MGL_LET('floorCount', 2, $floorCount + 1)"];
 ```
 
 ```swift
-NSExpression(format: "FUNCTION($floorCount + 1, 'mgl_expressionWithContext:', %@)",
-             ["floorCount": 2])
+NSExpression(format: "MGL_LET(floorCount, 2, $floorCount + 1)")
 ```
diff --git a/platform/darwin/src/MGLCircleStyleLayer.h b/platform/darwin/src/MGLCircleStyleLayer.h
index 2523637179..aa2d07db26 100644
--- a/platform/darwin/src/MGLCircleStyleLayer.h
+++ b/platform/darwin/src/MGLCircleStyleLayer.h
@@ -83,7 +83,7 @@ typedef NS_ENUM(NSUInteger, MGLCircleTranslationAnchor) {
  let layer = MGLCircleStyleLayer(identifier: "circles", source: population)
  layer.sourceLayerIdentifier = "population"
  layer.circleColor = NSExpression(forConstantValue: UIColor.green)
- layer.circleRadius = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.75, %@)",
+ layer.circleRadius = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.75, %@)",
                                    [12: 2,
                                     22: 180])
  layer.circleOpacity = NSExpression(forConstantValue: 0.7)
diff --git a/platform/darwin/src/MGLHeatmapStyleLayer.h b/platform/darwin/src/MGLHeatmapStyleLayer.h
index ff2b92f226..1c68e2cae8 100644
--- a/platform/darwin/src/MGLHeatmapStyleLayer.h
+++ b/platform/darwin/src/MGLHeatmapStyleLayer.h
@@ -35,10 +35,10 @@ NS_ASSUME_NONNULL_BEGIN
 
  ```swift
  let layer = MGLHeatmapStyleLayer(identifier: "earthquake-heat", source: earthquakes)
- layer.heatmapWeight = NSExpression(format: "FUNCTION(magnitude, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+ layer.heatmapWeight = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(magnitude, 'linear', nil, %@)",
                                     [0: 0,
                                      6: 1])
- layer.heatmapIntensity = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+ layer.heatmapIntensity = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                        [0: 1,
                                         9: 3])
  mapView.style?.addLayer(layer)
diff --git a/platform/darwin/src/MGLLineStyleLayer.h b/platform/darwin/src/MGLLineStyleLayer.h
index bdb5464ebc..d8e109d559 100644
--- a/platform/darwin/src/MGLLineStyleLayer.h
+++ b/platform/darwin/src/MGLLineStyleLayer.h
@@ -93,7 +93,7 @@ typedef NS_ENUM(NSUInteger, MGLLineTranslationAnchor) {
  ```swift
  let layer = MGLLineStyleLayer(identifier: "trails-path", source: trails)
  layer.sourceLayerIdentifier = "trails"
- layer.lineWidth = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.5, %@)",
+ layer.lineWidth = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
                                 [14: 2,
                                  18: 20])
  layer.lineColor = NSExpression(forConstantValue: UIColor.brown)
diff --git a/platform/darwin/src/MGLStyleValue.h b/platform/darwin/src/MGLStyleValue.h
index f6e9c51729..65f89c5909 100644
--- a/platform/darwin/src/MGLStyleValue.h
+++ b/platform/darwin/src/MGLStyleValue.h
@@ -8,13 +8,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 typedef NSString *MGLStyleFunctionOption NS_STRING_ENUM NS_UNAVAILABLE;
 
-extern MGL_EXPORT const MGLStyleFunctionOption MGLStyleFunctionOptionInterpolationBase __attribute__((unavailable("Use NSExpression instead, applying the mgl_interpolateWithCurveType:parameters:stops: function with a curve type of “exponential” and a non-nil parameter.")));
+extern MGL_EXPORT const MGLStyleFunctionOption MGLStyleFunctionOptionInterpolationBase __attribute__((unavailable("Use NSExpression instead, applying the mgl_interpolate:withCurveType:parameters:stops: function with a curve type of “exponential” and a non-nil parameter.")));
 
 extern MGL_EXPORT const MGLStyleFunctionOption MGLStyleFunctionOptionDefaultValue __attribute__((unavailable("Use +[NSExpression expressionForConditional:trueExpression:falseExpression:] instead.")));
 
 typedef NS_ENUM(NSUInteger, MGLInterpolationMode) {
-    MGLInterpolationModeExponential __attribute__((unavailable("Use NSExpression instead, applying the mgl_interpolateWithCurveType:parameters:stops: function with a curve type of “exponential”."))) = 0,
-    MGLInterpolationModeInterval __attribute__((unavailable("Use NSExpression instead, calling the mgl_stepWithMinimum:stops: function."))),
+    MGLInterpolationModeExponential __attribute__((unavailable("Use NSExpression instead, applying the mgl_interpolate:withCurveType:parameters:stops: function with a curve type of “exponential”."))) = 0,
+    MGLInterpolationModeInterval __attribute__((unavailable("Use NSExpression instead, calling the mgl_step:from:stops: function."))),
     MGLInterpolationModeCategorical __attribute__((unavailable("Use NSExpression instead."))),
     MGLInterpolationModeIdentity __attribute__((unavailable("Use +[NSExpression expressionForKeyPath:] instead.")))
 } __attribute__((unavailable("Use NSExpression instead.")));
@@ -29,19 +29,19 @@ MGL_EXPORT __attribute__((unavailable("Use +[NSExpression expressionForConstantV
 
 @compatibility_alias MGLStyleConstantValue MGLConstantStyleValue;
 
-MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, calling the mgl_stepWithMinimum:stops: or mgl_interpolateWithCurveType:parameters:stops: function.")))
+MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, calling the mgl_step:from:stops: or mgl_interpolate:withCurveType:parameters:stops: function.")))
 @interface MGLStyleFunction<T> : MGLStyleValue<T>
 @end
 
-MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, applying the mgl_stepWithMinimum:stops: or mgl_interpolateWithCurveType:parameters:stops: function to the $zoomLevel variable.")))
+MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, applying the mgl_step:from:stops: or mgl_interpolate:withCurveType:parameters:stops: function to the $zoomLevel variable.")))
 @interface MGLCameraStyleFunction<T> : MGLStyleFunction<T>
 @end
 
-MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, applying the mgl_stepWithMinimum:stops: or mgl_interpolateWithCurveType:parameters:stops: function to a key path expression.")))
+MGL_EXPORT __attribute__((unavailable("Use NSExpression instead, applying the mgl_step:from:stops: or mgl_interpolate:withCurveType:parameters:stops: function to a key path expression.")))
 @interface MGLSourceStyleFunction<T> : MGLStyleFunction<T>
 @end
 
-MGL_EXPORT __attribute__((unavailable("Use a NSExpression instead with nested mgl_stepWithMinimum:stops: or mgl_interpolateWithCurveType:parameters:stops: function calls.")))
+MGL_EXPORT __attribute__((unavailable("Use a NSExpression instead with nested mgl_step:from:stops: or mgl_interpolate:withCurveType:parameters:stops: function calls.")))
 @interface MGLCompositeStyleFunction<T> : MGLStyleFunction<T>
 @end
 
diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index a193b85caa..7fe8ce3c91 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -11,8 +11,168 @@
 #import "NSPredicate+MGLAdditions.h"
 #import "NSValue+MGLStyleAttributeAdditions.h"
 
+#import <objc/runtime.h>
+
 #import <mbgl/style/expression/expression.hpp>
 
+@interface MGLAftermarketExpressionInstaller: NSObject
+@end
+
+@implementation MGLAftermarketExpressionInstaller
+
++ (void)load {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        [self installFunctions];
+    });
+}
+
+/**
+ Adds to NSExpression’s built-in repertoire of functions.
+ */
++ (void)installFunctions {
+    Class MGLAftermarketExpressionInstaller = [self class];
+    
+    // NSExpression’s built-in functions are backed by class methods on a
+    // private class, so use a function expression to get at the class.
+    // http://funwithobjc.tumblr.com/post/2922267976/using-custom-functions-with-nsexpression
+    NSExpression *functionExpression = [NSExpression expressionWithFormat:@"sum({})"];
+    NSString *className = NSStringFromClass([functionExpression.operand.constantValue class]);
+    
+    // Effectively categorize the class with some extra class methods.
+    Class NSPredicateUtilities = objc_getMetaClass(className.UTF8String);
+#pragma clang push
+#pragma clang diagnostic ignored "-Wundeclared-selector"
+    #define INSTALL_METHOD(sel) \
+        { \
+            Method method = class_getInstanceMethod(MGLAftermarketExpressionInstaller, @selector(sel)); \
+            class_addMethod(NSPredicateUtilities, @selector(sel), method_getImplementation(method), method_getTypeEncoding(method)); \
+        }
+    #define INSTALL_CONTROL_STRUCTURE(sel) \
+        { \
+            Method method = class_getInstanceMethod(MGLAftermarketExpressionInstaller, @selector(sel:)); \
+            class_addMethod(NSPredicateUtilities, @selector(sel), method_getImplementation(method), method_getTypeEncoding(method)); \
+            class_addMethod(NSPredicateUtilities, @selector(sel:), method_getImplementation(method), method_getTypeEncoding(method)); \
+        }
+    
+    // Install method-like functions, taking the number of arguments implied by
+    // the selector name.
+    INSTALL_METHOD(mgl_join:);
+    INSTALL_METHOD(mgl_interpolate:withCurveType:parameters:stops:);
+    INSTALL_METHOD(mgl_step:from:stops:);
+    INSTALL_METHOD(mgl_coalesce:);
+    INSTALL_METHOD(mgl_does:have:);
+    
+    // Install functions that resemble control structures, taking arbitrary
+    // numbers of arguments. Vararg aftermarket functions need to be declared
+    // with an explicit and implicit first argument.
+    INSTALL_CONTROL_STRUCTURE(MGL_LET);
+    INSTALL_CONTROL_STRUCTURE(MGL_MATCH);
+    INSTALL_CONTROL_STRUCTURE(MGL_IF);
+    INSTALL_CONTROL_STRUCTURE(MGL_FUNCTION);
+    
+    #undef INSTALL_AFTERMARKET_FN
+#pragma clang pop
+}
+
+/**
+ Joins the given components into a single string by concatenating each component
+ in order.
+ */
+- (NSString *)mgl_join:(NSArray<NSString *> *)components {
+    return [components componentsJoinedByString:@""];
+}
+
+/**
+ A placeholder for a method that evaluates an interpolation expression.
+ */
+- (id)mgl_interpolate:(id)inputExpression withCurveType:(NSString *)curveType parameters:(NSDictionary *)params stops:(NSDictionary *)stops {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Interpolation expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+/**
+ A placeholder for a method that evaluates a step expression.
+ */
+- (id)mgl_step:(id)inputExpression from:(id)minimumExpression stops:(NSDictionary *)stops {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Step expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+/**
+ A placeholder for a method that evaluates a coalesce expression.
+ */
+- (id)mgl_coalesce:(NSArray<NSExpression *> *)elements {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Coalesce expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+/**
+ Returns a Boolean value indicating whether the object has a value for the given
+ key.
+ */
+- (BOOL)mgl_does:(id)object have:(NSString *)key {
+    return [object valueForKey:key] != nil;
+}
+
+/**
+ A placeholder for a method that evaluates an expression based on an arbitrary
+ number of variable names and assigned expressions.
+ */
+- (id)MGL_LET:(NSString *)firstVariableName, ... {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Assignment expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+/**
+ A placeholder for a method that evaluates an expression and returns the matching element.
+ */
+- (id)MGL_MATCH:(id)firstCondition, ... {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Assignment expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+/**
+ A placeholder for a method that evaluates an expression and returns the matching element.
+ */
+- (id)MGL_IF:(id)firstCondition, ... {
+    va_list argumentList;
+    va_start(argumentList, firstCondition);
+    
+    for (id eachExpression = firstCondition; eachExpression; eachExpression = va_arg(argumentList, id)) {
+        if ([eachExpression isKindOfClass:[NSComparisonPredicate class]]) {
+            id valueExpression = va_arg(argumentList, id);
+            if ([eachExpression evaluateWithObject:nil]) {
+                return valueExpression;
+            }
+        } else {
+            return eachExpression;
+        }
+    }
+    va_end(argumentList);
+    
+    return nil;
+}
+
+
+/**
+ A placeholder for a catch-all method that evaluates an arbitrary number of
+ arguments as an expression according to the Mapbox Style Specification’s
+ expression language.
+ */
+- (id)MGL_FUNCTION:(id)firstArgument, ... {
+    [NSException raise:NSInvalidArgumentException
+                format:@"Mapbox GL function expressions lack underlying Objective-C implementations."];
+    return nil;
+}
+
+@end
+
 @implementation NSExpression (MGLPrivateAdditions)
 
 - (std::vector<mbgl::Value>)mgl_aggregateMBGLValue {
@@ -260,7 +420,7 @@
 
 - (id)mgl_coalesce {
     [NSException raise:NSInvalidArgumentException
-                format:@"Coalesce expressions lack underlying Objective-C implementations."];
+                      format:@"Coalesce expressions lack underlying Objective-C implementations."];
     return nil;
 }
 
@@ -330,6 +490,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"^": @"raise:toPower:",
             @"upcase": @"uppercase:",
             @"downcase": @"lowercase:",
+            @"let": @"MGL_LET",
         };
     });
     
@@ -382,12 +543,15 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionForFunction:operand selectorName:@"boolValue" arguments:@[]];
         } else if ([op isEqualToString:@"to-number"]) {
             NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects.firstObject];
+            if (argumentObjects.count == 1) {
+                return [NSExpression expressionWithFormat:@"CAST(%@, 'NSNumber')", operand];
+            }
             argumentObjects = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
             return [NSExpression expressionForFunction:operand selectorName:@"mgl_numberWithFallbackValues:" arguments:subexpressions];
         } else if ([op isEqualToString:@"to-string"]) {
             NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects.firstObject];
-            return [NSExpression expressionForFunction:operand selectorName:@"stringValue" arguments:@[]];
+            return [NSExpression expressionWithFormat:@"CAST(%@, 'NSString')", operand];
         } else if ([op isEqualToString:@"get"]) {
             if (argumentObjects.count == 2) {
                 NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects.lastObject];
@@ -400,7 +564,12 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionForKeyPath:argumentObjects.firstObject];
         } else if ([op isEqualToString:@"length"]) {
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
-            return [NSExpression expressionForFunction:@"count:" arguments:@[subexpressions.firstObject]];
+            NSString *function = @"count:";
+            if ([subexpressions.firstObject expressionType] == NSConstantValueExpressionType
+                && [[subexpressions.firstObject constantValue] isKindOfClass:[NSString class]]) {
+                function = @"length:";
+            }
+            return [NSExpression expressionForFunction:function arguments:@[subexpressions.firstObject]];
         } else if ([op isEqualToString:@"min"]) {
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
             NSExpression *subexpression = [NSExpression expressionForAggregate:subexpressions];
@@ -415,9 +584,8 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionForConstantValue:@(M_PI)];
         } else if ([op isEqualToString:@"concat"]) {
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
-            NSExpression *operand = subexpressions.firstObject;
-            subexpressions = [subexpressions subarrayWithRange:NSMakeRange(1, subexpressions.count - 1)];
-            return [NSExpression expressionForFunction:operand selectorName:@"stringByAppendingString:" arguments:subexpressions];
+            NSExpression *subexpression = [NSExpression expressionForAggregate:subexpressions];
+            return [NSExpression expressionForFunction:@"mgl_join:" arguments:@[subexpression]];
         }  else if ([op isEqualToString:@"at"]) {
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
             NSExpression *index = subexpressions.firstObject;
@@ -425,9 +593,9 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionForFunction:@"objectFrom:withIndex:" arguments:@[operand, index]];
         } else if ([op isEqualToString:@"has"]) {
             NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects);
-            NSExpression *operand = argumentObjects.count > 1 ? subexpressions[1] : [NSExpression expressionWithFormat:@"self"];
-            NSExpression *property = subexpressions.firstObject;
-            return [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_has:', %@)", operand, property];
+            NSExpression *operand = argumentObjects.count > 1 ? subexpressions[1] : [NSExpression expressionForEvaluatedObject];
+            NSExpression *key = subexpressions.firstObject;
+            return [NSExpression expressionForFunction:@"mgl_does:have:" arguments:@[operand, key]];
         } else if ([op isEqualToString:@"interpolate"]) {
             NSArray *interpolationOptions = argumentObjects.firstObject;
             NSString *curveType = interpolationOptions.firstObject;
@@ -440,7 +608,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             }
             NSExpression *curveParameterExpression = [NSExpression mgl_expressionWithJSONObject:curveParameters];
             argumentObjects = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
-            NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects.firstObject];
+            NSExpression *inputExpression = [NSExpression mgl_expressionWithJSONObject:argumentObjects.firstObject];
             NSArray *stopExpressions = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
             NSMutableDictionary *stops = [NSMutableDictionary dictionaryWithCapacity:stopExpressions.count / 2];
             NSEnumerator *stopEnumerator = stopExpressions.objectEnumerator;
@@ -449,11 +617,10 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 stops[key] = [NSExpression mgl_expressionWithJSONObject:valueExpression];
             }
             NSExpression *stopExpression = [NSExpression expressionForConstantValue:stops];
-            return [NSExpression expressionForFunction:operand
-                                          selectorName:@"mgl_interpolateWithCurveType:parameters:stops:"
-                                             arguments:@[curveTypeExpression, curveParameterExpression, stopExpression]];
+            return [NSExpression expressionForFunction:@"mgl_interpolate:withCurveType:parameters:stops:"
+                                             arguments:@[inputExpression, curveTypeExpression, curveParameterExpression, stopExpression]];
         } else if ([op isEqualToString:@"step"]) {
-            NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects[0]];
+            NSExpression *inputExpression = [NSExpression mgl_expressionWithJSONObject:argumentObjects[0]];
             NSArray *stopExpressions = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
             NSExpression *minimum;
             if (stopExpressions.count % 2) {
@@ -471,9 +638,8 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 }
             }
             NSExpression *stopExpression = [NSExpression expressionForConstantValue:stops];
-            return [NSExpression expressionForFunction:operand
-                                          selectorName:@"mgl_stepWithMinimum:stops:"
-                                             arguments:@[minimum, stopExpression]];
+            return [NSExpression expressionForFunction:@"mgl_step:from:stops:"
+                                             arguments:@[inputExpression, minimum, stopExpression]];
         } else if ([op isEqualToString:@"zoom"]) {
             return [NSExpression expressionForVariable:@"zoomLevel"];
         } else if ([op isEqualToString:@"heatmap-density"]) {
@@ -484,48 +650,37 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionForVariable:@"mgl_featureIdentifier"];
         }  else if ([op isEqualToString:@"properties"]) {
             return [NSExpression expressionForVariable:@"mgl_featureProperties"];
-        } else if ([op isEqualToString:@"let"]) {
-            NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects.lastObject];
-            NSArray *bindingObjects = [argumentObjects subarrayWithRange:NSMakeRange(0, argumentObjects.count - 1)];
-            NSMutableDictionary *context = [NSMutableDictionary dictionaryWithCapacity:bindingObjects.count / 2];
-            NSEnumerator *bindingEnumerator = bindingObjects.objectEnumerator;
-            while (NSString *key = bindingEnumerator.nextObject) {
-                context[key] = [NSExpression mgl_expressionWithJSONObject:bindingEnumerator.nextObject];
-            }
-            return [NSExpression expressionForFunction:operand
-                                          selectorName:@"mgl_expressionWithContext:"
-                                             arguments:@[[NSExpression expressionForConstantValue:context]]];
         } else if ([op isEqualToString:@"var"]) {
             return [NSExpression expressionForVariable:argumentObjects.firstObject];
         } else if ([op isEqualToString:@"case"]) {
-            NSArray *caseExpressions = argumentObjects;
-            NSExpression *firstConditional = [NSExpression expressionWithFormat:@"%@", [NSPredicate mgl_predicateWithJSONObject:caseExpressions[0]]];
             NSMutableArray *arguments = [NSMutableArray array];
             
-            for (NSUInteger index = 1; index < caseExpressions.count; index++) {
-                if ([caseExpressions[index] isKindOfClass:[NSArray class]]) {
-                    NSPredicate *conditional = [NSPredicate mgl_predicateWithJSONObject:caseExpressions[index]];
+            for (NSUInteger index = 0; index < argumentObjects.count; index++) {
+                if ([argumentObjects[index] isKindOfClass:[NSArray class]]) {
+                    NSPredicate *conditional = [NSPredicate mgl_predicateWithJSONObject:argumentObjects[index]];
                     NSExpression *argument = [NSExpression expressionWithFormat:@"%@", conditional];
                     [arguments addObject:argument];
                 } else {
-                    [arguments addObject:[NSExpression mgl_expressionWithJSONObject:caseExpressions[index]]];
+                    [arguments addObject:[NSExpression mgl_expressionWithJSONObject:argumentObjects[index]]];
                 }
             }
             
-            return [NSExpression expressionForFunction:firstConditional selectorName:@"mgl_case:" arguments:arguments];
+            if (@available(iOS 9.0, *)) {
+                if (arguments.count == 3) {
+                    NSPredicate *conditional = [NSPredicate mgl_predicateWithJSONObject:argumentObjects.firstObject];
+                    return [NSExpression expressionForConditional:conditional trueExpression:arguments[1] falseExpression:arguments[2]];
+                }
+            }
+            return [NSExpression expressionForFunction:@"MGL_IF" arguments:arguments];
         } else if ([op isEqualToString:@"match"]) {
-            NSExpression *operand = [NSExpression mgl_expressionWithJSONObject:argumentObjects[0]];
-            NSArray *matchOptions = [argumentObjects subarrayWithRange:NSMakeRange(1, argumentObjects.count - 1)];
-
             NSMutableArray *optionsArray = [NSMutableArray array];
-            NSEnumerator *optionsEnumerator = matchOptions.objectEnumerator;
+            NSEnumerator *optionsEnumerator = argumentObjects.objectEnumerator;
             while (id object = optionsEnumerator.nextObject) {
                 NSExpression *option = [NSExpression mgl_expressionWithJSONObject:object];
                 [optionsArray addObject:option];
             }
         
-            return [NSExpression expressionForFunction:operand
-                                          selectorName:@"mgl_match:"
+            return [NSExpression expressionForFunction:@"MGL_MATCH"
                                              arguments:optionsArray];
         } else if ([op isEqualToString:@"coalesce"]) {
             NSMutableArray *expressions = [NSMutableArray array];
@@ -533,10 +688,10 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 [expressions addObject:[NSExpression mgl_expressionWithJSONObject:operand]];
             }
             
-            return [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_coalesce')", expressions];
-        }else {
-            [NSException raise:NSInvalidArgumentException
-                        format:@"Expression operator %@ not yet implemented.", op];
+            return [NSExpression expressionWithFormat:@"mgl_coalesce(%@)", expressions];
+        } else {
+            NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(array);
+            return [NSExpression expressionForFunction:@"MGL_FUNCTION" arguments:subexpressions];
         }
     }
     
@@ -561,6 +716,10 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             @"raise:toPower:": @"^",
             @"uppercase:": @"upcase",
             @"lowercase:": @"downcase",
+            @"length:": @"length",
+            // Vararg aftermarket expressions need to be declared with an explicit and implicit first argument.
+            @"MGL_LET": @"let",
+            @"MGL_LET:": @"let",
         };
     });
     
@@ -673,6 +832,9 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             } else if ([function isEqualToString:@"floor:"]) {
                 return [NSExpression expressionWithFormat:@"trunc:(%@) - TERNARY(modulus:by:(%@, 1) < 0, 1, 0)",
                         self.arguments.firstObject, self.arguments.firstObject].mgl_jsonExpressionObject;
+            } else if ([function isEqualToString:@"mgl_join:"]) {
+                NSArray *arguments = [self.arguments.firstObject.collection valueForKeyPath:@"mgl_jsonExpressionObject"];
+                return [@[@"concat"] arrayByAddingObjectsFromArray:arguments];
             } else if ([function isEqualToString:@"stringByAppendingString:"]) {
                 NSArray *arguments = self.arguments.mgl_jsonExpressionObject;
                 return [@[@"concat", self.operand.mgl_jsonExpressionObject] arrayByAddingObjectsFromArray:arguments];
@@ -690,46 +852,15 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 return @[@"to-string", self.operand.mgl_jsonExpressionObject];
             } else if ([function isEqualToString:@"noindex:"]) {
                 return self.arguments.firstObject.mgl_jsonExpressionObject;
-            } else if ([function isEqualToString:@"mgl_has:"]) {
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"has", self.arguments[0].mgl_jsonExpressionObject, nil];
-                if (self.operand.expressionType != NSEvaluatedObjectExpressionType) {
-                    [expressionObject addObject:self.operand.mgl_jsonExpressionObject];
-                }
-                return expressionObject;
-            } else if ([function isEqualToString:@"mgl_interpolateWithCurveType:parameters:stops:"]) {
-                if (self.arguments.count < 3) {
-                    [NSException raise:NSInvalidArgumentException format:
-                     @"Too few arguments to ‘mgl_interpolateWithCurveType:parameters:stops:’ function; expected 3 arguments."];
-                } else if (self.arguments.count > 3) {
-                    [NSException raise:NSInvalidArgumentException format:
-                     @"%lu unexpected arguments to ‘mgl_interpolateWithCurveType:parameters:stops:’ function; expected 3 arguments.",
-                     self.arguments.count - 3];
-                }
-                NSString *curveType = self.arguments.firstObject.constantValue;
-                NSMutableArray *interpolationArray = [NSMutableArray arrayWithObject:curveType];
-                if ([curveType isEqualToString:@"exponential"]) {
-                    id base = [self.arguments[1] mgl_jsonExpressionObject];
-                    [interpolationArray addObject:base];
-                } else if ([curveType isEqualToString:@"cubic-bezier"]) {
-                    NSArray *controlPoints = [self.arguments[1].collection mgl_jsonExpressionObject];
-                    [interpolationArray addObjectsFromArray:controlPoints];
-                }
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"interpolate", interpolationArray, self.operand.mgl_jsonExpressionObject, nil];
-                NSDictionary<NSNumber *, NSExpression *> *stops = self.arguments[2].constantValue;
-                for (NSNumber *key in [stops.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
-                    [expressionObject addObject:key];
-                    [expressionObject addObject:[stops[key] mgl_jsonExpressionObject]];
-                }
-                return expressionObject;
-            } else if ([function isEqualToString:@"mgl_stepWithMinimum:stops:"]) {
-                id minimum = self.arguments.firstObject.mgl_jsonExpressionObject;
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"step", self.operand.mgl_jsonExpressionObject, minimum, nil];
-                NSDictionary<NSNumber *, NSExpression *> *stops = self.arguments[1].constantValue;
-                for (NSNumber *key in [stops.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
-                    [expressionObject addObject:key];
-                    [expressionObject addObject:[stops[key] mgl_jsonExpressionObject]];
-                }
-                return expressionObject;
+            } else if ([function isEqualToString:@"mgl_does:have:"] ||
+                       [function isEqualToString:@"mgl_has:"]) {
+                return self.mgl_jsonHasExpressionObject;
+            } else if ([function isEqualToString:@"mgl_interpolate:withCurveType:parameters:stops:"]
+                       || [function isEqualToString:@"mgl_interpolateWithCurveType:parameters:stops:"]) {
+                return self.mgl_jsonInterpolationExpressionObject;
+            } else if ([function isEqualToString:@"mgl_step:from:stops:"]
+                       || [function isEqualToString:@"mgl_stepWithMinimum:stops:"]) {
+                return self.mgl_jsonStepExpressionObject;
             } else if ([function isEqualToString:@"mgl_expressionWithContext:"]) {
                 id context = self.arguments.firstObject;
                 if ([context isKindOfClass:[NSExpression class]]) {
@@ -742,37 +873,28 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 }];
                 [expressionObject addObject:self.operand.mgl_jsonExpressionObject];
                 return expressionObject;
-            } else if ([function isEqualToString:@"mgl_case:"]) {
-                NSPredicate *firstConditional = (NSPredicate *)self.operand.constantValue;
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"case", firstConditional.mgl_jsonExpressionObject, nil];
-
-                for (NSExpression *option in self.arguments) {
-                    if ([option respondsToSelector:@selector(constantValue)] && [option.constantValue isKindOfClass:[NSComparisonPredicate class]]) {
-                        NSPredicate *predicate = (NSPredicate *)option.constantValue;
-                        [expressionObject addObject:predicate.mgl_jsonExpressionObject];
-                    } else {
-                        [expressionObject addObject:option.mgl_jsonExpressionObject];
-                    }
-                }
-
-                return expressionObject;
-            } else if ([function isEqualToString:@"mgl_match:"]) {
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"match", self.operand.mgl_jsonExpressionObject, nil];
+            } else if ([function isEqualToString:@"MGL_IF"] ||
+                       [function isEqualToString:@"mgl_if:"]) {
+                return self.mgl_jsonIfExpressionObject;
+            } else if ([function isEqualToString:@"MGL_MATCH"] ||
+                       [function isEqualToString:@"mgl_match:"]) {
+                return self.mgl_jsonMatchExpressionObject;
+            } else if ([function isEqualToString:@"mgl_coalesce:"] ||
+                       [function isEqualToString:@"mgl_coalesce"]) {
                 
-
-                for (NSExpression *option in self.arguments) {
-                    [expressionObject addObject:option.mgl_jsonExpressionObject];
-                }
-                
-                return expressionObject;
-            } else if ([function isEqualToString:@"mgl_coalesce"]) {
-                NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"coalesce", nil];
-                
-                for (NSExpression *expression in self.operand.constantValue) {
-                    [expressionObject addObject:[expression mgl_jsonExpressionObject]];
+                return self.mgl_jsonCoalesceExpressionObject;
+            } else if ([function isEqualToString:@"castObject:toType:"]) {
+                id object = self.arguments.firstObject.mgl_jsonExpressionObject;
+                NSString *type = self.arguments[1].mgl_jsonExpressionObject;
+                if ([type isEqualToString:@"NSString"]) {
+                    return @[@"to-string", object];
+                } else if ([type isEqualToString:@"NSNumber"]) {
+                    return @[@"to-number", object];
                 }
-                
-                return expressionObject;
+                [NSException raise:NSInvalidArgumentException
+                            format:@"Casting expression to %@ not yet implemented.", type];
+            } else if ([function isEqualToString:@"MGL_FUNCTION"]) {
+                return self.arguments.mgl_jsonExpressionObject;
             } else if ([function isEqualToString:@"median:"] ||
                        [function isEqualToString:@"mode:"] ||
                        [function isEqualToString:@"stddev:"] ||
@@ -851,4 +973,121 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
     return nil;
 }
 
+- (id)mgl_jsonInterpolationExpressionObject {
+    NSUInteger expectedArgumentCount = [self.function componentsSeparatedByString:@":"].count - 1;
+    if (self.arguments.count < expectedArgumentCount) {
+        [NSException raise:NSInvalidArgumentException format:
+         @"Too few arguments to ‘%@’ function; expected %lu arguments.",
+         self.function, expectedArgumentCount];
+    } else if (self.arguments.count > expectedArgumentCount) {
+        [NSException raise:NSInvalidArgumentException format:
+         @"%lu unexpected arguments to ‘%@’ function; expected %lu arguments.",
+         self.arguments.count - expectedArgumentCount, self.function, expectedArgumentCount];
+    }
+    
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"mgl_interpolate:withCurveType:parameters:stops:"];
+    NSUInteger curveTypeIndex = isAftermarketFunction ? 1 : 0;
+    NSString *curveType = self.arguments[curveTypeIndex].constantValue;
+    NSMutableArray *interpolationArray = [NSMutableArray arrayWithObject:curveType];
+    if ([curveType isEqualToString:@"exponential"]) {
+        id base = [self.arguments[curveTypeIndex + 1] mgl_jsonExpressionObject];
+        [interpolationArray addObject:base];
+    } else if ([curveType isEqualToString:@"cubic-bezier"]) {
+        NSArray *controlPoints = [self.arguments[curveTypeIndex + 1].collection mgl_jsonExpressionObject];
+        [interpolationArray addObjectsFromArray:controlPoints];
+    }
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"interpolate", interpolationArray, nil];
+    [expressionObject addObject:(isAftermarketFunction ? self.arguments.firstObject : self.operand).mgl_jsonExpressionObject];
+    NSDictionary<NSNumber *, NSExpression *> *stops = self.arguments[curveTypeIndex + 2].constantValue;
+    for (NSNumber *key in [stops.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
+        [expressionObject addObject:key];
+        [expressionObject addObject:[stops[key] mgl_jsonExpressionObject]];
+    }
+    return expressionObject;
+}
+
+- (id)mgl_jsonStepExpressionObject {
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"mgl_step:from:stops:"];
+    NSUInteger minimumIndex = isAftermarketFunction ? 1 : 0;
+    id minimum = self.arguments[minimumIndex].mgl_jsonExpressionObject;
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"step", (isAftermarketFunction ? self.arguments.firstObject : self.operand).mgl_jsonExpressionObject, minimum, nil];
+    NSDictionary<NSNumber *, NSExpression *> *stops = self.arguments[minimumIndex + 1].constantValue;
+    for (NSNumber *key in [stops.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
+        [expressionObject addObject:key];
+        [expressionObject addObject:[stops[key] mgl_jsonExpressionObject]];
+    }
+    return expressionObject;
+}
+
+- (id)mgl_jsonMatchExpressionObject {
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"MGL_MATCH"];
+    NSUInteger minimumIndex = isAftermarketFunction ? 1 : 0;
+
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"match", (isAftermarketFunction ? self.arguments.firstObject : self.operand).mgl_jsonExpressionObject, nil];
+    NSArray<NSExpression *> *arguments = isAftermarketFunction ? self.arguments : self.arguments[minimumIndex].constantValue;
+    
+    for (NSUInteger index = minimumIndex; index < arguments.count; index++) {
+        [expressionObject addObject:arguments[index].mgl_jsonExpressionObject];
+    }
+    
+    return expressionObject;
+}
+
+- (id)mgl_jsonIfExpressionObject {
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"MGL_IF"];
+    NSUInteger minimumIndex = isAftermarketFunction ? 1 : 0;
+    NSExpression *firstCondition;
+    id condition;
+    
+    if (isAftermarketFunction) {
+        firstCondition = self.arguments.firstObject;
+    } else {
+        firstCondition = self.operand;
+    }
+    
+    if ([firstCondition respondsToSelector:@selector(constantValue)] && [firstCondition.constantValue isKindOfClass:[NSComparisonPredicate class]]) {
+        NSPredicate *predicate = (NSPredicate *)firstCondition.constantValue;
+        condition = predicate.mgl_jsonExpressionObject;
+    } else {
+        condition = firstCondition.mgl_jsonExpressionObject;
+    }
+    
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"case", condition, nil];
+    NSArray<NSExpression *> *arguments = isAftermarketFunction ? self.arguments : self.arguments[minimumIndex].constantValue;
+    
+    for (NSUInteger index = minimumIndex; index < arguments.count; index++) {
+        if ([arguments[index] respondsToSelector:@selector(constantValue)] && [arguments[index].constantValue isKindOfClass:[NSComparisonPredicate class]]) {
+            NSPredicate *predicate = (NSPredicate *)arguments[index].constantValue;
+            [expressionObject addObject:predicate.mgl_jsonExpressionObject];
+        } else {
+            [expressionObject addObject:arguments[index].mgl_jsonExpressionObject];
+        }
+    }
+    
+    return expressionObject;
+}
+
+- (id)mgl_jsonCoalesceExpressionObject {
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"mgl_coalesce:"];
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"coalesce", nil];
+    
+    for (NSExpression *expression in  (isAftermarketFunction ? self.arguments.firstObject : self.operand).constantValue) {
+        [expressionObject addObject:[expression mgl_jsonExpressionObject]];
+    }
+    
+    return expressionObject;
+}
+
+- (id)mgl_jsonHasExpressionObject {
+    BOOL isAftermarketFunction = [self.function isEqualToString:@"mgl_does:have:"];
+    NSExpression *operand = isAftermarketFunction ? self.arguments[0] : self.operand;
+    NSExpression *key = self.arguments[isAftermarketFunction ? 1 : 0];
+
+    NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"has", key.mgl_jsonExpressionObject, nil];
+    if (operand.expressionType != NSEvaluatedObjectExpressionType) {
+        [expressionObject addObject:operand.mgl_jsonExpressionObject];
+    }
+    return expressionObject;
+}
+
 @end
diff --git a/platform/darwin/src/NSExpression+MGLPrivateAdditions.h b/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
index f726dd3e71..d255cfdb0f 100644
--- a/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
+++ b/platform/darwin/src/NSExpression+MGLPrivateAdditions.h
@@ -54,8 +54,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (nonatomic, readonly) id mgl_jsonExpressionObject;
 
-@property (nonatomic, readonly) id mgl_coalesce;
-
 @end
 
 @interface NSDictionary (MGLExpressionAdditions)
diff --git a/platform/darwin/src/NSPredicate+MGLAdditions.h b/platform/darwin/src/NSPredicate+MGLAdditions.h
index a67c6ca005..a73b1a61ba 100644
--- a/platform/darwin/src/NSPredicate+MGLAdditions.h
+++ b/platform/darwin/src/NSPredicate+MGLAdditions.h
@@ -16,7 +16,7 @@
 
 @property (nonatomic, readonly) id mgl_jsonExpressionObject;
 
-- (id)mgl_case:(id)firstValue, ...;
+- (id)mgl_if:(id)firstValue, ...;
 
 - (id)mgl_match:(NSExpression *)firstCase, ...;
 
diff --git a/platform/darwin/src/NSPredicate+MGLAdditions.mm b/platform/darwin/src/NSPredicate+MGLAdditions.mm
index 1a7bb30a92..8fe5735bf9 100644
--- a/platform/darwin/src/NSPredicate+MGLAdditions.mm
+++ b/platform/darwin/src/NSPredicate+MGLAdditions.mm
@@ -324,34 +324,34 @@ NSArray *MGLSubpredicatesWithJSONObjects(NSArray *objects) {
     return nil;
 }
 
-- (id)mgl_case:(id)firstValue, ... {
+- (id)mgl_if:(id)firstValue, ... {
 
     if ([self evaluateWithObject:nil]) {
-        return firstValue;
-    }
-    
+            return firstValue;
+        }
+
     id eachExpression;
     va_list argumentList;
     va_start(argumentList, firstValue);
-    
+
     while ((eachExpression = va_arg(argumentList, id))) {
-        if ([eachExpression isKindOfClass:[NSComparisonPredicate class]]) {
-            id valueExpression = va_arg(argumentList, id);
-            if ([eachExpression evaluateWithObject:nil]) {
-                return valueExpression;
-            }
-        } else {
-            return eachExpression;
+            if ([eachExpression isKindOfClass:[NSComparisonPredicate class]]) {
+                    id valueExpression = va_arg(argumentList, id);
+                    if ([eachExpression evaluateWithObject:nil]) {
+                            return valueExpression;
+                        }
+                } else {
+                        return eachExpression;
+                    }
         }
-    }
     va_end(argumentList);
-    
+
     return nil;
 }
 
 - (id)mgl_match:(NSExpression *)firstCase, ... {
     [NSException raise:NSInvalidArgumentException
-                format:@"Match expressions lack underlying Objective-C implementations."];
+                      format:@"Match expressions lack underlying Objective-C implementations."];
     return nil;
 }
 
diff --git a/platform/darwin/test/MGLBackgroundStyleLayerTests.mm b/platform/darwin/test/MGLBackgroundStyleLayerTests.mm
index e7c2982413..de8080f425 100644
--- a/platform/darwin/test/MGLBackgroundStyleLayerTests.mm
+++ b/platform/darwin/test/MGLBackgroundStyleLayerTests.mm
@@ -42,7 +42,7 @@
                               @"backgroundColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.backgroundColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -66,8 +66,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.backgroundColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.backgroundColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.backgroundColorTransition = transitionTest;
@@ -95,7 +95,7 @@
                               @"backgroundOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.backgroundOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -119,8 +119,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.backgroundOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.backgroundOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.backgroundOpacityTransition = transitionTest;
@@ -148,7 +148,7 @@
                               @"backgroundPattern should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Background Pattern'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.backgroundPattern = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -172,8 +172,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.backgroundPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.backgroundPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLBackgroundLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.backgroundPatternTransition = transitionTest;
diff --git a/platform/darwin/test/MGLCircleStyleLayerTests.mm b/platform/darwin/test/MGLCircleStyleLayerTests.mm
index 7677344580..cb950a1feb 100644
--- a/platform/darwin/test/MGLCircleStyleLayerTests.mm
+++ b/platform/darwin/test/MGLCircleStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"circleBlur should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleBlur = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -77,7 +77,7 @@
         XCTAssertEqualObjects(layer.circleBlur, functionExpression,
                               @"circleBlur should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleBlur = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -88,7 +88,7 @@
         XCTAssertEqualObjects(layer.circleBlur, functionExpression,
                               @"circleBlur should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleBlur = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -133,7 +133,7 @@
                               @"circleColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -147,7 +147,7 @@
         XCTAssertEqualObjects(layer.circleColor, functionExpression,
                               @"circleColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -158,7 +158,7 @@
         XCTAssertEqualObjects(layer.circleColor, functionExpression,
                               @"circleColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -203,7 +203,7 @@
                               @"circleOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -217,7 +217,7 @@
         XCTAssertEqualObjects(layer.circleOpacity, functionExpression,
                               @"circleOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -228,7 +228,7 @@
         XCTAssertEqualObjects(layer.circleOpacity, functionExpression,
                               @"circleOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -273,7 +273,7 @@
                               @"circlePitchAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circlePitchAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::AlignmentType> intervalStops = {{
@@ -297,8 +297,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.circlePitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.circlePitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -317,7 +317,7 @@
                               @"circleRadius should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleRadius = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -331,7 +331,7 @@
         XCTAssertEqualObjects(layer.circleRadius, functionExpression,
                               @"circleRadius should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleRadius = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -342,7 +342,7 @@
         XCTAssertEqualObjects(layer.circleRadius, functionExpression,
                               @"circleRadius should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleRadius = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -387,7 +387,7 @@
                               @"circleScaleAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleScaleAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::CirclePitchScaleType> intervalStops = {{
@@ -411,8 +411,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.circleScaleAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.circleScaleAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -431,7 +431,7 @@
                               @"circleStrokeColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleStrokeColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -445,7 +445,7 @@
         XCTAssertEqualObjects(layer.circleStrokeColor, functionExpression,
                               @"circleStrokeColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleStrokeColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -456,7 +456,7 @@
         XCTAssertEqualObjects(layer.circleStrokeColor, functionExpression,
                               @"circleStrokeColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleStrokeColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -501,7 +501,7 @@
                               @"circleStrokeOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleStrokeOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -515,7 +515,7 @@
         XCTAssertEqualObjects(layer.circleStrokeOpacity, functionExpression,
                               @"circleStrokeOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleStrokeOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -526,7 +526,7 @@
         XCTAssertEqualObjects(layer.circleStrokeOpacity, functionExpression,
                               @"circleStrokeOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleStrokeOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -571,7 +571,7 @@
                               @"circleStrokeWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleStrokeWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -585,7 +585,7 @@
         XCTAssertEqualObjects(layer.circleStrokeWidth, functionExpression,
                               @"circleStrokeWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.circleStrokeWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -596,7 +596,7 @@
         XCTAssertEqualObjects(layer.circleStrokeWidth, functionExpression,
                               @"circleStrokeWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.circleStrokeWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -647,7 +647,7 @@
                               @"circleTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -671,8 +671,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.circleTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.circleTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -691,7 +691,7 @@
                               @"circleTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.circleTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -715,8 +715,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.circleTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.circleTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLCircleLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 }
diff --git a/platform/darwin/test/MGLDocumentationExampleTests.swift b/platform/darwin/test/MGLDocumentationExampleTests.swift
index a216d9ad1c..5a112f07e2 100644
--- a/platform/darwin/test/MGLDocumentationExampleTests.swift
+++ b/platform/darwin/test/MGLDocumentationExampleTests.swift
@@ -162,7 +162,7 @@ class MGLDocumentationExampleTests: XCTestCase, MGLMapViewDelegate {
         #else
             layer.circleColor = NSExpression(forConstantValue: UIColor.green)
         #endif
-        layer.circleRadius = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.75, %@)",
+        layer.circleRadius = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.75, %@)",
                                           [12: 2,
                                            22: 180])
         layer.circleOpacity = NSExpression(forConstantValue: 0.7)
@@ -180,7 +180,7 @@ class MGLDocumentationExampleTests: XCTestCase, MGLMapViewDelegate {
         //#-example-code
         let layer = MGLLineStyleLayer(identifier: "trails-path", source: trails)
         layer.sourceLayerIdentifier = "trails"
-        layer.lineWidth = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.5, %@)",
+        layer.lineWidth = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
                                        [14: 2,
                                         18: 20])
         #if os(macOS)
@@ -237,10 +237,10 @@ class MGLDocumentationExampleTests: XCTestCase, MGLMapViewDelegate {
         
         //#-example-code
         let layer = MGLHeatmapStyleLayer(identifier: "earthquake-heat", source: earthquakes)
-        layer.heatmapWeight = NSExpression(format: "FUNCTION(magnitude, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+        layer.heatmapWeight = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(magnitude, 'linear', nil, %@)",
                                            [0: 0,
                                             6: 1])
-        layer.heatmapIntensity = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+        layer.heatmapIntensity = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                               [0: 1,
                                                9: 3])
         mapView.style?.addLayer(layer)
diff --git a/platform/darwin/test/MGLDocumentationGuideTests.swift b/platform/darwin/test/MGLDocumentationGuideTests.swift
index f939695f32..8769bc4428 100644
--- a/platform/darwin/test/MGLDocumentationGuideTests.swift
+++ b/platform/darwin/test/MGLDocumentationGuideTests.swift
@@ -71,7 +71,7 @@ class MGLDocumentationGuideTests: XCTestCase, MGLMapViewDelegate {
         #endif
         //#-end-example-code
         
-        let _ = NSExpression(format: "FUNCTION(mag, 'mgl_stepWithMinimum:stops:', %@, %@)",
+        let _ = NSExpression(format: "mgl_step:from:stops:(mag, %@, %@)",
                              stops[0]!, stops)
     }
     
@@ -104,10 +104,10 @@ class MGLDocumentationGuideTests: XCTestCase, MGLMapViewDelegate {
         
         let layer = MGLCircleStyleLayer(identifier: "circles", source: source)
         #if os(macOS)
-            layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+            layer.circleColor = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(mag, 'linear', nil, %@)",
                                              stops)
         #else
-            layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+            layer.circleColor = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(mag, 'linear', nil, %@)",
                                              stops)
         #endif
         layer.circleRadius = NSExpression(forConstantValue: 10)
@@ -126,7 +126,7 @@ class MGLDocumentationGuideTests: XCTestCase, MGLMapViewDelegate {
             18: 18,
         ]
         
-        layer.circleRadius = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.5, %@)",
+        layer.circleRadius = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
                                           stops)
         //#-end-example-code
     }
@@ -145,7 +145,7 @@ class MGLDocumentationGuideTests: XCTestCase, MGLMapViewDelegate {
                 10: .white,
             ]
             
-            layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_stepWithMinimum:stops:', %@, %@)",
+            layer.circleColor = NSExpression(format: "mgl_step:from:stops:(mag, %@, %@)",
                                              NSColor.green, stops)
         #else
             let stops: [Float: UIColor] = [
@@ -156,7 +156,7 @@ class MGLDocumentationGuideTests: XCTestCase, MGLMapViewDelegate {
                 10: .white,
             ]
             
-            layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_stepWithMinimum:stops:', %@, %@)",
+            layer.circleColor = NSExpression(format: "mgl_step:from:stops:(mag, %@, %@)",
                                              UIColor.green, stops)
         #endif
         //#-end-example-code
diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index d189b41cd7..bcc708e51e 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -199,9 +199,11 @@ using namespace std::string_literals;
     }
     {
         NSDictionary *context = @{@"loremIpsum": MGLConstantExpression(@"Lorem ipsum dolor sit amet")};
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(uppercase($loremIpsum), 'mgl_expressionWithContext:', %@)", context];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_LET('loremIpsum', 'Lorem ipsum dolor sit amet', uppercase($loremIpsum))", context];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(uppercase($loremIpsum), 'mgl_expressionWithContext:', %@)", context];
         NSArray *jsonExpression = @[@"let", @"loremIpsum", @"Lorem ipsum dolor sit amet", @[@"upcase", @[@"var", @"loremIpsum"]]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
 }
@@ -353,6 +355,15 @@ using namespace std::string_literals;
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
+        NSArray *arguments = @[MGLConstantExpression(@1), MGLConstantExpression(@1), MGLConstantExpression(@1)];
+        NSExpression *expression = [NSExpression expressionForFunction:@"add:to:" arguments:arguments];
+        NSArray *jsonExpression = @[@"+", @1, @1, @1];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        jsonExpression = @[@"+", @[@"+", @1, @1], @1];
+        XCTAssertEqualObjects([NSExpression expressionWithFormat:@"1 + 1 + 1"].mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], [NSExpression expressionWithFormat:@"1 + 1 + 1"]);
+    }
+    {
         NSExpression *expression = [NSExpression expressionForFunction:@"from:subtract:" arguments:arguments];
         NSArray *jsonExpression = @[@"-", @1, @1];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
@@ -510,10 +521,13 @@ using namespace std::string_literals;
     NSArray *arguments = @[MGLConstantExpression(@"MacDonald")];
     {
         NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION('Old', 'stringByAppendingString:', 'MacDonald')"];
+        NSExpression *aftermarketExpression = [NSExpression expressionWithFormat:@"mgl_join({'Old', 'MacDonald'})"];
         NSArray *jsonExpression = @[@"concat", @"Old", @"MacDonald"];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(aftermarketExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @"OldMacDonald");
-        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+        XCTAssertEqualObjects([aftermarketExpression expressionValueWithObject:nil context:nil], @"OldMacDonald");
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], aftermarketExpression);
     }
     {
         NSExpression *expression = [NSExpression expressionForFunction:@"uppercase:" arguments:arguments];
@@ -527,6 +541,12 @@ using namespace std::string_literals;
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
+    {
+        NSExpression *expression = [NSExpression expressionForFunction:@"length:" arguments:arguments];
+        NSArray *jsonExpression = @[@"length", @"MacDonald"];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+    }
 }
 
 - (void)testTypeConversionExpressionObject {
@@ -551,10 +571,22 @@ using namespace std::string_literals;
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(number, 'stringValue')"];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(postalCode, 'NSNumber')"];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(postalCode, 'mgl_numberWithFallbackValues:')"];
+        NSArray *jsonExpression = @[@"to-number", @[@"get", @"postalCode"]];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:@{@"postalCode": @"02134"} context:nil], @02134);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(number, 'NSString')"];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(number, 'stringValue')"];
         NSArray *jsonExpression = @[@"to-string", @[@"get", @"number"]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([expression expressionValueWithObject:@{@"number": @1.5} context:nil], @"1.5");
+        XCTAssertEqualObjects([compatibilityExpression expressionValueWithObject:@{@"number": @1.5} context:nil], @"1.5");
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
 }
@@ -562,46 +594,57 @@ using namespace std::string_literals;
 - (void)testInterpolationExpressionObject {
     {
         NSDictionary *stops = @{@0: MGLConstantExpression(@100), @10: MGLConstantExpression(@200)};
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", stops];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(x, 'linear', nil, %@)", stops];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", stops];
         NSArray *jsonExpression = @[@"interpolate", @[@"linear"], @[@"get", @"x"], @0, @100, @10, @200];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
         NSDictionary *stops = @{@1: MGLConstantExpression(@2), @3: MGLConstantExpression(@6)};
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 2, %@)", stops];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(x, 'exponential', 2, %@)", stops];
         NSArray *jsonExpression = @[@"interpolate", @[@"exponential", @2], @[@"get", @"x"], @1, @2, @3, @6];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
         NSDictionary *stops = @{@0: MGLConstantExpression(@0), @100: MGLConstantExpression(@100)};
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_interpolateWithCurveType:parameters:stops:', 'cubic-bezier', { 0.42, 0, 0.58, 1 }, %@)", stops];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(x, 'cubic-bezier', { 0.42, 0, 0.58, 1 }, %@)", stops];
         NSArray *jsonExpression = @[@"interpolate", @[@"cubic-bezier", @0.42, @0, @0.58, @1], @[@"get", @"x"], @0, @0, @100, @100];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
         NSDictionary *stops = @{@0: MGLConstantExpression(@111), @1: MGLConstantExpression(@1111)};
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_stepWithMinimum:stops:', 11, %@)", stops];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(x, 11, %@)", stops];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(x, 'mgl_stepWithMinimum:stops:', 11, %@)", stops];
         NSArray *jsonExpression = @[@"step", @[@"get", @"x"], @11, @0, @111, @1, @1111];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
 }
 
 - (void)testMatchExpressionObject {
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(2 - 1, 'mgl_match:', %@, %@, %@, %@, 'default')", MGLConstantExpression(@1),
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_MATCH(2 - 1,  %@, %@, %@, %@, 'default')", MGLConstantExpression(@1),
                                     MGLConstantExpression(@"one"),
                                     MGLConstantExpression(@0),
                                     MGLConstantExpression(@"zero")];
+        NSExpression *predicate = [NSExpression expressionWithFormat:@"2 - 1"];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_match:', %@)", predicate, @[MGLConstantExpression(@1),
+                                                 MGLConstantExpression(@"one"),
+                                                 MGLConstantExpression(@0),
+                                                 MGLConstantExpression(@"zero"),
+                                                 MGLConstantExpression(@"default")]];
         NSArray *jsonExpression =  @[@"match", @[@"-", @2, @1], @1, @"one", @0, @"zero", @"default"];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(2 * 1, 'mgl_match:', %@, %@, 'default')", MGLConstantExpression(@1), MGLConstantExpression(@"one")];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_MATCH(2 * 1, %@, %@, 'default')", MGLConstantExpression(@1), MGLConstantExpression(@"one")];
         NSArray *jsonExpression =  @[@"match", @[@"*", @2, @1], @1, @"one", @"default"];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
@@ -610,35 +653,71 @@ using namespace std::string_literals;
 
 - (void)testCoalesceExpressionObject {
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_coalesce')", @[[NSExpression expressionForKeyPath:@"x"],
-                                                                                                     [NSExpression expressionForKeyPath:@"y"],
-                                                                                                     [NSExpression expressionForKeyPath:@"z"],
-                                                                                                     [NSExpression expressionForConstantValue:@0]]];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"mgl_coalesce(%@)",
+                                    @[[NSExpression expressionForKeyPath:@"x"],
+                                      [NSExpression expressionForKeyPath:@"y"],
+                                      [NSExpression expressionForKeyPath:@"z"],
+                                      [NSExpression expressionForConstantValue:@0]]];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_coalesce')", @[[NSExpression expressionForKeyPath:@"x"],
+                                                                                                                      [NSExpression expressionForKeyPath:@"y"],
+                                                                                                                      [NSExpression expressionForKeyPath:@"z"],
+                                                                                                                      [NSExpression expressionForConstantValue:@0]]];
         NSArray *jsonExpression = @[@"coalesce", @[@"get", @"x"], @[@"get", @"y"], @[@"get", @"z"], @0];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     
 }
 
 - (void)testConditionalExpressionObject {
-    {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_case:', %@, %@)",
+    // This test crashes on iOS 8, which doesn't have `+[NSExpression expressionForConditional:trueExpression:falseExpression:]`.
+    // https://github.com/mapbox/mapbox-gl-native/issues/11007
+    if (@available(iOS 9.0, *)) {
+        {
+            NSPredicate *conditional = [NSPredicate predicateWithFormat:@"1 = 2"];
+            NSExpression *trueExpression = [NSExpression expressionForConstantValue:@YES];
+            NSExpression *falseExpression = [NSExpression expressionForConstantValue:@NO];
+            NSExpression *expression = [NSExpression expressionForConditional:conditional trueExpression:trueExpression falseExpression:falseExpression];
+            NSArray *jsonExpression = @[@"case", @[@"==", @1, @2], @YES, @NO];
+            XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+            XCTAssertEqualObjects([NSExpression expressionWithFormat:@"TERNARY(1 = 2, TRUE, FALSE)"].mgl_jsonExpressionObject, jsonExpression);
+            XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @NO);
+            XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+        }
+        {
+            NSExpression *expression = [NSExpression expressionWithFormat:@"TERNARY(0 = 1, TRUE, TERNARY(1 = 2, TRUE, FALSE))"];
+            NSArray *jsonExpression = @[@"case", @[@"==", @0, @1], @YES, @[@"==", @1, @2], @YES, @NO];
+            XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+            XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @NO);
+            expression = [NSExpression expressionWithFormat:@"MGL_IF(%@, TRUE, %@, TRUE, FALSE)",
+                          MGLConstantExpression([NSPredicate predicateWithFormat:@"0 = 1"]),
+                          MGLConstantExpression([NSPredicate predicateWithFormat:@"1 = 2"])];
+            XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+        }
+    }
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_IF(%@, %@, %@)",
                                     [NSExpression expressionWithFormat:@"%@", [NSPredicate predicateWithFormat:@"1 = 2"]],
-                                                                                                 MGLConstantExpression(@YES),
-                                                                                                 MGLConstantExpression(@NO)];
+                                    MGLConstantExpression(@YES),
+                                    MGLConstantExpression(@NO)];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_if:', %@)", [NSPredicate predicateWithFormat:@"1 = 2"], @[MGLConstantExpression(@YES), MGLConstantExpression(@NO)]];
         NSArray *jsonExpression = @[@"case", @[@"==", @1, @2], @YES, @NO];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
+        if (@available(iOS 9.0, *)) {
+            expression = [NSExpression expressionWithFormat:@"TERNARY(1 = 2, YES, NO)"];
+        }
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
         XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @NO);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_case:', %@, %@, %@, %@)",
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_IF(%@, %@, %@, %@, %@)",
                                     [NSExpression expressionWithFormat:@"%@", [NSPredicate predicateWithFormat:@"1 = 2"]],
-                                                                                                 MGLConstantExpression(@YES),
-                                                                                                 [NSExpression expressionWithFormat:@"%@", [NSPredicate predicateWithFormat:@"1 = 1"]],
-                                                                                                 MGLConstantExpression(@YES),
-                                                                                                 MGLConstantExpression(@NO)];
+                                    MGLConstantExpression(@YES),
+                                    [NSExpression expressionWithFormat:@"%@", [NSPredicate predicateWithFormat:@"1 = 1"]],
+                                    MGLConstantExpression(@YES),
+                                    MGLConstantExpression(@NO)];
         NSArray *jsonExpression = @[@"case", @[@"==", @1, @2], @YES, @[@"==", @1, @1], @YES, @NO];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
@@ -650,40 +729,91 @@ using namespace std::string_literals;
 - (void)testLookupExpressionObject {
     {
         NSExpression *array = [NSExpression expressionForAggregate:@[MGLConstantExpression(@9),
-                                                                         MGLConstantExpression(@8),
-                                                                         MGLConstantExpression(@7)]];
-        NSExpression *expression = [NSExpression expressionForFunction:@"objectFrom:withIndex:" arguments:@[array, MGLConstantExpression(@1)]];
+                                                                     MGLConstantExpression(@8),
+                                                                     MGLConstantExpression(@7)]];
+        NSExpression *expression = [NSExpression expressionForFunction:@"objectFrom:withIndex:"
+                                                             arguments:@[array, MGLConstantExpression(@1)]];
         NSArray *jsonExpression = @[@"at", @1, @[ @"literal", @[@9, @8, @7]]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
         NSExpression *array = [NSExpression expressionForAggregate:@[MGLConstantExpression(@9),
-                                                                       MGLConstantExpression(@8),
-                                                                       MGLConstantExpression(@7)]];
-        NSExpression *expression = [NSExpression expressionForFunction:@"objectFrom:withIndex:" arguments:@[array, [NSExpression expressionForKeyPath:@"x"]]];
+                                                                     MGLConstantExpression(@8),
+                                                                     MGLConstantExpression(@7)]];
+        NSExpression *expression = [NSExpression expressionForFunction:@"objectFrom:withIndex:"
+                                                             arguments:@[array, [NSExpression expressionForKeyPath:@"x"]]];
         NSArray *jsonExpression = @[@"at", @[@"get", @"x"], @[ @"literal", @[@9, @8, @7]]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(self, 'mgl_has:', 'x')"];
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_does:have:"
+                                                             arguments:@[[NSExpression expressionForEvaluatedObject],
+                                                                         [NSExpression expressionForConstantValue:@"x"]]];
+        NSExpression *compatibilityExpression = [NSExpression expressionWithFormat:@"FUNCTION(self, 'mgl_has:', 'x')"];
         NSArray *jsonExpression = @[@"has", @"x"];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects(compatibilityExpression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_has:', 'x')", [NSExpression expressionForConstantValue:@{@"x": MGLConstantExpression(@0)}]];
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_does:have:"
+                                                             arguments:@[MGLConstantExpression(@{@"x": MGLConstantExpression(@0)}),
+                                                                         MGLConstantExpression(@"x")]];
         NSArray *jsonExpression = @[@"has", @"x",  @[@"literal", @{@"x": @0}]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION($mgl_featureProperties, 'mgl_has:', 'x')"];
+        NSExpression *expression = [NSExpression expressionForFunction:@"mgl_does:have:"
+                                                             arguments:@[[NSExpression expressionForVariable:@"mgl_featureProperties"],
+                                                                         [NSExpression expressionForConstantValue:@"x"]]];
         NSArray *jsonExpression = @[@"has", @"x", @[@"properties"]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
     }
+    {
+        NSExpression *expression;
+        if (@available(iOS 9.0, *)) {
+            expression = [NSExpression expressionWithFormat:@"TERNARY(key != nil, 1, 0)"];
+        } else {
+            expression = [NSExpression expressionWithFormat:@"MGL_IF(%@, 1, 0)",
+                          MGLConstantExpression([NSPredicate predicateWithFormat:@"key != nil"])];
+        }
+        NSArray *jsonExpression = @[@"case", @[@"!=", @[@"get", @"key"], [NSNull null]], @1, @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:@{} context:nil], @NO);
+        XCTAssertEqualObjects([expression expressionValueWithObject:@{@"key": @"🗝"} context:nil], @YES);
+    }
+    {
+        NSDictionary *dictionary = @{@"key": @"🔑"};
+        NSExpression *expression;
+        if (@available(iOS 9.0, *)) {
+            expression = [NSExpression expressionWithFormat:@"TERNARY(%@.key != nil, 1, 0)", dictionary];
+        } else {
+            NSPredicate *conditional = [NSPredicate predicateWithFormat:@"%@.key != nil", dictionary];
+            expression = [NSExpression expressionWithFormat:@"MGL_IF(%@, 1, 0)",
+                          MGLConstantExpression(conditional)];
+        }
+        NSArray *jsonExpression = @[@"case", @[@"!=", @[@"get", @"key", @[@"literal", dictionary]], [NSNull null]], @1, @0];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        // The dictionary isn’t equal enough.
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression].description, expression.description);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @YES);
+    }
+}
+
+- (void)testGenericExpressionObject {
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"MGL_FUNCTION('random', 1, 2, 3, 4, 5)"];
+        NSArray *jsonExpression = @[@"random", @1, @2, @3, @4, @5];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression);
+        expression = [NSExpression expressionWithFormat:@"MGL_FUNCTION('random', 1, 2, 3, 4)"];
+        XCTAssertThrowsSpecificNamed([expression expressionValueWithObject:nil context:nil], NSException, NSInvalidArgumentException);
+    }
 }
 
 @end
diff --git a/platform/darwin/test/MGLFillExtrusionStyleLayerTests.mm b/platform/darwin/test/MGLFillExtrusionStyleLayerTests.mm
index f5e26381d6..876386948c 100644
--- a/platform/darwin/test/MGLFillExtrusionStyleLayerTests.mm
+++ b/platform/darwin/test/MGLFillExtrusionStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"fillExtrusionBase should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionBase = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -77,7 +77,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionBase, functionExpression,
                               @"fillExtrusionBase should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillExtrusionBase = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -88,7 +88,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionBase, functionExpression,
                               @"fillExtrusionBase should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillExtrusionBase = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -133,7 +133,7 @@
                               @"fillExtrusionColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -147,7 +147,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionColor, functionExpression,
                               @"fillExtrusionColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillExtrusionColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -158,7 +158,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionColor, functionExpression,
                               @"fillExtrusionColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillExtrusionColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -203,7 +203,7 @@
                               @"fillExtrusionHeight should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionHeight = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -217,7 +217,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionHeight, functionExpression,
                               @"fillExtrusionHeight should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillExtrusionHeight = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -228,7 +228,7 @@
         XCTAssertEqualObjects(layer.fillExtrusionHeight, functionExpression,
                               @"fillExtrusionHeight should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillExtrusionHeight = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -273,7 +273,7 @@
                               @"fillExtrusionOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -297,8 +297,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.fillExtrusionOpacityTransition = transitionTest;
@@ -326,7 +326,7 @@
                               @"fillExtrusionPattern should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Fill Extrusion Pattern'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionPattern = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -350,8 +350,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.fillExtrusionPatternTransition = transitionTest;
@@ -385,7 +385,7 @@
                               @"fillExtrusionTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -409,8 +409,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -429,7 +429,7 @@
                               @"fillExtrusionTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillExtrusionTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -453,8 +453,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillExtrusionTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillExtrusionLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 }
diff --git a/platform/darwin/test/MGLFillStyleLayerTests.mm b/platform/darwin/test/MGLFillStyleLayerTests.mm
index 25521f3ede..8fa349c135 100644
--- a/platform/darwin/test/MGLFillStyleLayerTests.mm
+++ b/platform/darwin/test/MGLFillStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"fillAntialiased should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"false"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillAntialiased = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -87,8 +87,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillAntialiased = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillAntialiased = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -107,7 +107,7 @@
                               @"fillColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -121,7 +121,7 @@
         XCTAssertEqualObjects(layer.fillColor, functionExpression,
                               @"fillColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -132,7 +132,7 @@
         XCTAssertEqualObjects(layer.fillColor, functionExpression,
                               @"fillColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -177,7 +177,7 @@
                               @"fillOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -191,7 +191,7 @@
         XCTAssertEqualObjects(layer.fillOpacity, functionExpression,
                               @"fillOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -202,7 +202,7 @@
         XCTAssertEqualObjects(layer.fillOpacity, functionExpression,
                               @"fillOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -247,7 +247,7 @@
                               @"fillOutlineColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillOutlineColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -261,7 +261,7 @@
         XCTAssertEqualObjects(layer.fillOutlineColor, functionExpression,
                               @"fillOutlineColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.fillOutlineColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -272,7 +272,7 @@
         XCTAssertEqualObjects(layer.fillOutlineColor, functionExpression,
                               @"fillOutlineColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.fillOutlineColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -317,7 +317,7 @@
                               @"fillPattern should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Fill Pattern'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillPattern = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -341,8 +341,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.fillPatternTransition = transitionTest;
@@ -376,7 +376,7 @@
                               @"fillTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -400,8 +400,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -420,7 +420,7 @@
                               @"fillTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.fillTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -444,8 +444,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.fillTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.fillTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLFillLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 }
diff --git a/platform/darwin/test/MGLHeatmapColorTests.mm b/platform/darwin/test/MGLHeatmapColorTests.mm
index 8d44064d94..ba28cc0345 100644
--- a/platform/darwin/test/MGLHeatmapColorTests.mm
+++ b/platform/darwin/test/MGLHeatmapColorTests.mm
@@ -33,7 +33,7 @@
 
     constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
     NSExpression *constantExpression2 = [NSExpression expressionWithFormat:@"%@", [MGLColor blueColor]];
-    NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($heatmapDensity, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@12: constantExpression2}];
+    NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($heatmapDensity, %@, %@)", constantExpression, @{@12: constantExpression2}];
     layer.heatmapColor = functionExpression;
     
     XCTAssertEqual(rawLayer->getHeatmapColor().evaluate(11.0), mbgl::Color::red(),
@@ -49,12 +49,12 @@
     XCTAssertEqualObjects(layer.heatmapColor, defaultExpression,
                           @"heatmapColor should return the default value after being unset.");
 
-    functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+    functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
     XCTAssertThrowsSpecificNamed(layer.heatmapColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera expression is applied to heatmapColor.");
     functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
     XCTAssertThrowsSpecificNamed(layer.heatmapColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a data expression is applied to heatmapColor.");
-    functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-    functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+    functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+    functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
     XCTAssertThrowsSpecificNamed(layer.heatmapColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
 }
 
diff --git a/platform/darwin/test/MGLHeatmapStyleLayerTests.mm b/platform/darwin/test/MGLHeatmapStyleLayerTests.mm
index 74121affd8..4b51c6cc62 100644
--- a/platform/darwin/test/MGLHeatmapStyleLayerTests.mm
+++ b/platform/darwin/test/MGLHeatmapStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"heatmapIntensity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.heatmapIntensity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -87,8 +87,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.heatmapIntensity = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.heatmapIntensity = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.heatmapIntensityTransition = transitionTest;
@@ -116,7 +116,7 @@
                               @"heatmapOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.heatmapOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -140,8 +140,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.heatmapOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.heatmapOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLHeatmapLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.heatmapOpacityTransition = transitionTest;
@@ -169,7 +169,7 @@
                               @"heatmapRadius should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.heatmapRadius = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -183,7 +183,7 @@
         XCTAssertEqualObjects(layer.heatmapRadius, functionExpression,
                               @"heatmapRadius should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.heatmapRadius = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -194,7 +194,7 @@
         XCTAssertEqualObjects(layer.heatmapRadius, functionExpression,
                               @"heatmapRadius should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.heatmapRadius = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -239,7 +239,7 @@
                               @"heatmapWeight should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.heatmapWeight = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -253,7 +253,7 @@
         XCTAssertEqualObjects(layer.heatmapWeight, functionExpression,
                               @"heatmapWeight should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.heatmapWeight = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -264,7 +264,7 @@
         XCTAssertEqualObjects(layer.heatmapWeight, functionExpression,
                               @"heatmapWeight should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.heatmapWeight = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
diff --git a/platform/darwin/test/MGLHillshadeStyleLayerTests.mm b/platform/darwin/test/MGLHillshadeStyleLayerTests.mm
index b0b7ddd5ee..34937d1674 100644
--- a/platform/darwin/test/MGLHillshadeStyleLayerTests.mm
+++ b/platform/darwin/test/MGLHillshadeStyleLayerTests.mm
@@ -45,7 +45,7 @@
                               @"hillshadeAccentColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeAccentColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -69,8 +69,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeAccentColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeAccentColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.hillshadeAccentColorTransition = transitionTest;
@@ -98,7 +98,7 @@
                               @"hillshadeExaggeration should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeExaggeration = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -122,8 +122,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeExaggeration = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeExaggeration = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.hillshadeExaggerationTransition = transitionTest;
@@ -151,7 +151,7 @@
                               @"hillshadeHighlightColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeHighlightColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -175,8 +175,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeHighlightColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeHighlightColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.hillshadeHighlightColorTransition = transitionTest;
@@ -204,7 +204,7 @@
                               @"hillshadeIlluminationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeIlluminationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::HillshadeIlluminationAnchorType> intervalStops = {{
@@ -228,8 +228,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeIlluminationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeIlluminationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -248,7 +248,7 @@
                               @"hillshadeIlluminationDirection should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeIlluminationDirection = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -272,8 +272,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeIlluminationDirection = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeIlluminationDirection = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -292,7 +292,7 @@
                               @"hillshadeShadowColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.hillshadeShadowColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -316,8 +316,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.hillshadeShadowColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.hillshadeShadowColor = functionExpression, NSException, NSInvalidArgumentException, @"MGLHillshadeLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.hillshadeShadowColorTransition = transitionTest;
diff --git a/platform/darwin/test/MGLLineStyleLayerTests.mm b/platform/darwin/test/MGLLineStyleLayerTests.mm
index bf98e98320..bbc382567b 100644
--- a/platform/darwin/test/MGLLineStyleLayerTests.mm
+++ b/platform/darwin/test/MGLLineStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"lineCap should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'square'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineCap = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::LineCapType> intervalStops = {{
@@ -87,8 +87,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineCap = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineCap = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -107,7 +107,7 @@
                               @"lineJoin should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'miter'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineJoin = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::LineJoinType> intervalStops = {{
@@ -145,7 +145,7 @@
                               @"lineMiterLimit should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineMiterLimit = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -169,8 +169,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineMiterLimit = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineMiterLimit = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -189,7 +189,7 @@
                               @"lineRoundLimit should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineRoundLimit = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -213,8 +213,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineRoundLimit = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineRoundLimit = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -233,7 +233,7 @@
                               @"lineBlur should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineBlur = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -247,7 +247,7 @@
         XCTAssertEqualObjects(layer.lineBlur, functionExpression,
                               @"lineBlur should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineBlur = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -258,7 +258,7 @@
         XCTAssertEqualObjects(layer.lineBlur, functionExpression,
                               @"lineBlur should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineBlur = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -303,7 +303,7 @@
                               @"lineColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -317,7 +317,7 @@
         XCTAssertEqualObjects(layer.lineColor, functionExpression,
                               @"lineColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -328,7 +328,7 @@
         XCTAssertEqualObjects(layer.lineColor, functionExpression,
                               @"lineColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -373,7 +373,7 @@
                               @"lineDashPattern should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 2}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineDashPattern = functionExpression;
 
         mbgl::style::IntervalStops<std::vector<float>> intervalStops = {{
@@ -397,8 +397,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineDashPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineDashPattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -417,7 +417,7 @@
                               @"lineGapWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineGapWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -431,7 +431,7 @@
         XCTAssertEqualObjects(layer.lineGapWidth, functionExpression,
                               @"lineGapWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineGapWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -442,7 +442,7 @@
         XCTAssertEqualObjects(layer.lineGapWidth, functionExpression,
                               @"lineGapWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineGapWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -487,7 +487,7 @@
                               @"lineOffset should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineOffset = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -501,7 +501,7 @@
         XCTAssertEqualObjects(layer.lineOffset, functionExpression,
                               @"lineOffset should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineOffset = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -512,7 +512,7 @@
         XCTAssertEqualObjects(layer.lineOffset, functionExpression,
                               @"lineOffset should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineOffset = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -557,7 +557,7 @@
                               @"lineOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -571,7 +571,7 @@
         XCTAssertEqualObjects(layer.lineOpacity, functionExpression,
                               @"lineOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -582,7 +582,7 @@
         XCTAssertEqualObjects(layer.lineOpacity, functionExpression,
                               @"lineOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -627,7 +627,7 @@
                               @"linePattern should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Line Pattern'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.linePattern = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -651,8 +651,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.linePattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.linePattern = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.linePatternTransition = transitionTest;
@@ -686,7 +686,7 @@
                               @"lineTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -710,8 +710,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -730,7 +730,7 @@
                               @"lineTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -754,8 +754,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.lineTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.lineTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLLineLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -774,7 +774,7 @@
                               @"lineWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.lineWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -788,7 +788,7 @@
         XCTAssertEqualObjects(layer.lineWidth, functionExpression,
                               @"lineWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.lineWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -799,7 +799,7 @@
         XCTAssertEqualObjects(layer.lineWidth, functionExpression,
                               @"lineWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.lineWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
diff --git a/platform/darwin/test/MGLRasterStyleLayerTests.mm b/platform/darwin/test/MGLRasterStyleLayerTests.mm
index 5ded23ee3c..c8e454743e 100644
--- a/platform/darwin/test/MGLRasterStyleLayerTests.mm
+++ b/platform/darwin/test/MGLRasterStyleLayerTests.mm
@@ -45,7 +45,7 @@
                               @"maximumRasterBrightness should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.maximumRasterBrightness = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -69,8 +69,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.maximumRasterBrightness = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.maximumRasterBrightness = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -89,7 +89,7 @@
                               @"minimumRasterBrightness should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.minimumRasterBrightness = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -113,8 +113,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.minimumRasterBrightness = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.minimumRasterBrightness = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -133,7 +133,7 @@
                               @"rasterContrast should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.rasterContrast = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -157,8 +157,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.rasterContrast = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.rasterContrast = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.rasterContrastTransition = transitionTest;
@@ -186,7 +186,7 @@
                               @"rasterFadeDuration should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.rasterFadeDuration = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -210,8 +210,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.rasterFadeDuration = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.rasterFadeDuration = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -230,7 +230,7 @@
                               @"rasterHueRotation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.rasterHueRotation = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -254,8 +254,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.rasterHueRotation = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.rasterHueRotation = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -274,7 +274,7 @@
                               @"rasterOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.rasterOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -298,8 +298,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.rasterOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.rasterOpacity = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.rasterOpacityTransition = transitionTest;
@@ -327,7 +327,7 @@
                               @"rasterSaturation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.rasterSaturation = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -351,8 +351,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.rasterSaturation = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.rasterSaturation = functionExpression, NSException, NSInvalidArgumentException, @"MGLRasterLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
         // Transition property test
         layer.rasterSaturationTransition = transitionTest;
diff --git a/platform/darwin/test/MGLStyleLayerTests.mm.ejs b/platform/darwin/test/MGLStyleLayerTests.mm.ejs
index e17501ed18..ef4ffdb42e 100644
--- a/platform/darwin/test/MGLStyleLayerTests.mm.ejs
+++ b/platform/darwin/test/MGLStyleLayerTests.mm.ejs
@@ -80,7 +80,7 @@
                               @"<%- objCName(property) %> should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:<%- objCTestValue(property, type, false, 3) %>];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.<%- objCName(property) %> = functionExpression;
 
         mbgl::style::IntervalStops<<%- mbglType(property) %>> intervalStops = {{
@@ -95,7 +95,7 @@
                               @"<%- objCName(property) %> should round-trip camera expressions.");
 
 <% if (property["property-function"] && isInterpolatable(property)) { -%>
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.<%- objCName(property) %> = functionExpression;
 
         mbgl::style::ExponentialStops<<%- mbglType(property) %>> exponentialStops = { {{18, <%- mbglTestValue(property, type) %>}}, 1.0 };
@@ -106,7 +106,7 @@
         XCTAssertEqualObjects(layer.<%- objCName(property) %>, functionExpression,
                               @"<%- objCName(property) %> should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.<%- objCName(property) %> = functionExpression;
 
         std::map<float, <%- mbglType(property) %>> innerStops { {18, <%- mbglTestValue(property, type) %>} };
@@ -131,8 +131,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.<%- objCName(property) %> = functionExpression, NSException, NSInvalidArgumentException, @"MGL<%- camelize(type) %>Layer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.<%- objCName(property) %> = functionExpression, NSException, NSInvalidArgumentException, @"MGL<%- camelize(type) %>Layer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
 <% } -%>
 <% if (property["transition"] && !property.original) { -%>
diff --git a/platform/darwin/test/MGLSymbolStyleLayerTests.mm b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
index 05e091b5c8..06ff058a8e 100644
--- a/platform/darwin/test/MGLSymbolStyleLayerTests.mm
+++ b/platform/darwin/test/MGLSymbolStyleLayerTests.mm
@@ -63,7 +63,7 @@
                               @"iconAllowsOverlap should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconAllowsOverlap = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -87,8 +87,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconAllowsOverlap = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconAllowsOverlap = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -107,7 +107,7 @@
                               @"iconAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'bottom-right'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::SymbolAnchorType> intervalStops = {{
@@ -145,7 +145,7 @@
                               @"iconIgnoresPlacement should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconIgnoresPlacement = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -169,8 +169,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconIgnoresPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconIgnoresPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -189,7 +189,7 @@
                               @"iconImageName should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Icon Image'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconImageName = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -233,7 +233,7 @@
                               @"iconOffset should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconOffset = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -247,7 +247,7 @@
         XCTAssertEqualObjects(layer.iconOffset, functionExpression,
                               @"iconOffset should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconOffset = functionExpression;
 
         mbgl::style::ExponentialStops<std::array<float, 2>> exponentialStops = { {{18, { 1, 1 }}}, 1.0 };
@@ -258,7 +258,7 @@
         XCTAssertEqualObjects(layer.iconOffset, functionExpression,
                               @"iconOffset should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconOffset = functionExpression;
 
         std::map<float, std::array<float, 2>> innerStops { {18, { 1, 1 }} };
@@ -294,7 +294,7 @@
                               @"iconOptional should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconOptional = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -318,8 +318,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconOptional = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconOptional = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -338,7 +338,7 @@
                               @"iconPadding should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconPadding = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -362,8 +362,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -382,7 +382,7 @@
                               @"iconPitchAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'auto'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconPitchAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::AlignmentType> intervalStops = {{
@@ -406,8 +406,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconPitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconPitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -426,7 +426,7 @@
                               @"iconRotation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconRotation = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -440,7 +440,7 @@
         XCTAssertEqualObjects(layer.iconRotation, functionExpression,
                               @"iconRotation should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconRotation = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -451,7 +451,7 @@
         XCTAssertEqualObjects(layer.iconRotation, functionExpression,
                               @"iconRotation should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconRotation = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -487,7 +487,7 @@
                               @"iconRotationAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'auto'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconRotationAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::AlignmentType> intervalStops = {{
@@ -511,8 +511,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconRotationAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconRotationAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -531,7 +531,7 @@
                               @"iconScale should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconScale = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -545,7 +545,7 @@
         XCTAssertEqualObjects(layer.iconScale, functionExpression,
                               @"iconScale should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconScale = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -556,7 +556,7 @@
         XCTAssertEqualObjects(layer.iconScale, functionExpression,
                               @"iconScale should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconScale = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -592,7 +592,7 @@
                               @"iconTextFit should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'both'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconTextFit = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::IconTextFitType> intervalStops = {{
@@ -616,8 +616,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconTextFit = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconTextFit = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -642,7 +642,7 @@
                               @"iconTextFitPadding should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1, 1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconTextFitPadding = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 4>> intervalStops = {{
@@ -666,8 +666,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconTextFitPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconTextFitPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -686,7 +686,7 @@
                               @"keepsIconUpright should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.keepsIconUpright = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -710,8 +710,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.keepsIconUpright = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.keepsIconUpright = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -730,7 +730,7 @@
                               @"keepsTextUpright should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"false"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.keepsTextUpright = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -754,8 +754,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.keepsTextUpright = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.keepsTextUpright = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -774,7 +774,7 @@
                               @"maximumTextAngle should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.maximumTextAngle = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -798,8 +798,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.maximumTextAngle = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.maximumTextAngle = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -818,7 +818,7 @@
                               @"maximumTextWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.maximumTextWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -832,7 +832,7 @@
         XCTAssertEqualObjects(layer.maximumTextWidth, functionExpression,
                               @"maximumTextWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.maximumTextWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -843,7 +843,7 @@
         XCTAssertEqualObjects(layer.maximumTextWidth, functionExpression,
                               @"maximumTextWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.maximumTextWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -879,7 +879,7 @@
                               @"symbolAvoidsEdges should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.symbolAvoidsEdges = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -903,8 +903,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.symbolAvoidsEdges = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.symbolAvoidsEdges = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -923,7 +923,7 @@
                               @"symbolPlacement should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'line'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.symbolPlacement = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::SymbolPlacementType> intervalStops = {{
@@ -947,8 +947,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.symbolPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.symbolPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -967,7 +967,7 @@
                               @"symbolSpacing should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.symbolSpacing = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -991,8 +991,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.symbolSpacing = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.symbolSpacing = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1011,7 +1011,7 @@
                               @"text should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'Text Field'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.text = functionExpression;
 
         mbgl::style::IntervalStops<std::string> intervalStops = {{
@@ -1049,7 +1049,7 @@
                               @"textAllowsOverlap should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textAllowsOverlap = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -1073,8 +1073,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textAllowsOverlap = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textAllowsOverlap = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1093,7 +1093,7 @@
                               @"textAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'bottom-right'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::SymbolAnchorType> intervalStops = {{
@@ -1131,7 +1131,7 @@
                               @"textFontNames should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{'Text Font', 'Tnof Txet'}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textFontNames = functionExpression;
 
         mbgl::style::IntervalStops<std::vector<std::string>> intervalStops = {{
@@ -1169,7 +1169,7 @@
                               @"textFontSize should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textFontSize = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1183,7 +1183,7 @@
         XCTAssertEqualObjects(layer.textFontSize, functionExpression,
                               @"textFontSize should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textFontSize = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -1194,7 +1194,7 @@
         XCTAssertEqualObjects(layer.textFontSize, functionExpression,
                               @"textFontSize should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textFontSize = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -1230,7 +1230,7 @@
                               @"textIgnoresPlacement should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textIgnoresPlacement = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -1254,8 +1254,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textIgnoresPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textIgnoresPlacement = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1274,7 +1274,7 @@
                               @"textJustification should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'right'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textJustification = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TextJustifyType> intervalStops = {{
@@ -1312,7 +1312,7 @@
                               @"textLetterSpacing should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textLetterSpacing = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1326,7 +1326,7 @@
         XCTAssertEqualObjects(layer.textLetterSpacing, functionExpression,
                               @"textLetterSpacing should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textLetterSpacing = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -1337,7 +1337,7 @@
         XCTAssertEqualObjects(layer.textLetterSpacing, functionExpression,
                               @"textLetterSpacing should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textLetterSpacing = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -1373,7 +1373,7 @@
                               @"textLineHeight should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textLineHeight = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1397,8 +1397,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textLineHeight = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textLineHeight = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1423,7 +1423,7 @@
                               @"textOffset should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textOffset = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -1437,7 +1437,7 @@
         XCTAssertEqualObjects(layer.textOffset, functionExpression,
                               @"textOffset should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textOffset = functionExpression;
 
         mbgl::style::ExponentialStops<std::array<float, 2>> exponentialStops = { {{18, { 1, 1 }}}, 1.0 };
@@ -1448,7 +1448,7 @@
         XCTAssertEqualObjects(layer.textOffset, functionExpression,
                               @"textOffset should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textOffset = functionExpression;
 
         std::map<float, std::array<float, 2>> innerStops { {18, { 1, 1 }} };
@@ -1484,7 +1484,7 @@
                               @"textOptional should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"true"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textOptional = functionExpression;
 
         mbgl::style::IntervalStops<bool> intervalStops = {{
@@ -1508,8 +1508,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textOptional = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textOptional = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1528,7 +1528,7 @@
                               @"textPadding should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textPadding = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1552,8 +1552,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textPadding = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1572,7 +1572,7 @@
                               @"textPitchAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'auto'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textPitchAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::AlignmentType> intervalStops = {{
@@ -1596,8 +1596,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textPitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textPitchAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1616,7 +1616,7 @@
                               @"textRotation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textRotation = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1630,7 +1630,7 @@
         XCTAssertEqualObjects(layer.textRotation, functionExpression,
                               @"textRotation should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textRotation = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -1641,7 +1641,7 @@
         XCTAssertEqualObjects(layer.textRotation, functionExpression,
                               @"textRotation should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textRotation = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -1677,7 +1677,7 @@
                               @"textRotationAlignment should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'auto'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textRotationAlignment = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::AlignmentType> intervalStops = {{
@@ -1701,8 +1701,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textRotationAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textRotationAlignment = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -1721,7 +1721,7 @@
                               @"textTransform should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'lowercase'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textTransform = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TextTransformType> intervalStops = {{
@@ -1759,7 +1759,7 @@
                               @"iconColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -1773,7 +1773,7 @@
         XCTAssertEqualObjects(layer.iconColor, functionExpression,
                               @"iconColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -1784,7 +1784,7 @@
         XCTAssertEqualObjects(layer.iconColor, functionExpression,
                               @"iconColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -1829,7 +1829,7 @@
                               @"iconHaloBlur should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconHaloBlur = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1843,7 +1843,7 @@
         XCTAssertEqualObjects(layer.iconHaloBlur, functionExpression,
                               @"iconHaloBlur should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconHaloBlur = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -1854,7 +1854,7 @@
         XCTAssertEqualObjects(layer.iconHaloBlur, functionExpression,
                               @"iconHaloBlur should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconHaloBlur = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -1899,7 +1899,7 @@
                               @"iconHaloColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconHaloColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -1913,7 +1913,7 @@
         XCTAssertEqualObjects(layer.iconHaloColor, functionExpression,
                               @"iconHaloColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconHaloColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -1924,7 +1924,7 @@
         XCTAssertEqualObjects(layer.iconHaloColor, functionExpression,
                               @"iconHaloColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconHaloColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -1969,7 +1969,7 @@
                               @"iconHaloWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconHaloWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -1983,7 +1983,7 @@
         XCTAssertEqualObjects(layer.iconHaloWidth, functionExpression,
                               @"iconHaloWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconHaloWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -1994,7 +1994,7 @@
         XCTAssertEqualObjects(layer.iconHaloWidth, functionExpression,
                               @"iconHaloWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconHaloWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -2039,7 +2039,7 @@
                               @"iconOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -2053,7 +2053,7 @@
         XCTAssertEqualObjects(layer.iconOpacity, functionExpression,
                               @"iconOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.iconOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -2064,7 +2064,7 @@
         XCTAssertEqualObjects(layer.iconOpacity, functionExpression,
                               @"iconOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.iconOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -2115,7 +2115,7 @@
                               @"iconTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -2139,8 +2139,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -2159,7 +2159,7 @@
                               @"iconTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.iconTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -2183,8 +2183,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.iconTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.iconTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -2203,7 +2203,7 @@
                               @"textColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -2217,7 +2217,7 @@
         XCTAssertEqualObjects(layer.textColor, functionExpression,
                               @"textColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -2228,7 +2228,7 @@
         XCTAssertEqualObjects(layer.textColor, functionExpression,
                               @"textColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -2273,7 +2273,7 @@
                               @"textHaloBlur should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textHaloBlur = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -2287,7 +2287,7 @@
         XCTAssertEqualObjects(layer.textHaloBlur, functionExpression,
                               @"textHaloBlur should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textHaloBlur = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -2298,7 +2298,7 @@
         XCTAssertEqualObjects(layer.textHaloBlur, functionExpression,
                               @"textHaloBlur should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textHaloBlur = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -2343,7 +2343,7 @@
                               @"textHaloColor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"%@", [MGLColor redColor]];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textHaloColor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::Color> intervalStops = {{
@@ -2357,7 +2357,7 @@
         XCTAssertEqualObjects(layer.textHaloColor, functionExpression,
                               @"textHaloColor should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textHaloColor = functionExpression;
 
         mbgl::style::ExponentialStops<mbgl::Color> exponentialStops = { {{18, { 1, 0, 0, 1 }}}, 1.0 };
@@ -2368,7 +2368,7 @@
         XCTAssertEqualObjects(layer.textHaloColor, functionExpression,
                               @"textHaloColor should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textHaloColor = functionExpression;
 
         std::map<float, mbgl::Color> innerStops { {18, { 1, 0, 0, 1 }} };
@@ -2413,7 +2413,7 @@
                               @"textHaloWidth should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textHaloWidth = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -2427,7 +2427,7 @@
         XCTAssertEqualObjects(layer.textHaloWidth, functionExpression,
                               @"textHaloWidth should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textHaloWidth = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -2438,7 +2438,7 @@
         XCTAssertEqualObjects(layer.textHaloWidth, functionExpression,
                               @"textHaloWidth should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textHaloWidth = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -2483,7 +2483,7 @@
                               @"textOpacity should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"0xff"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textOpacity = functionExpression;
 
         mbgl::style::IntervalStops<float> intervalStops = {{
@@ -2497,7 +2497,7 @@
         XCTAssertEqualObjects(layer.textOpacity, functionExpression,
                               @"textOpacity should round-trip camera expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(keyName, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:(keyName, 'linear', nil, %@)", @{@18: constantExpression}];
         layer.textOpacity = functionExpression;
 
         mbgl::style::ExponentialStops<float> exponentialStops = { {{18, 0xff}}, 1.0 };
@@ -2508,7 +2508,7 @@
         XCTAssertEqualObjects(layer.textOpacity, functionExpression,
                               @"textOpacity should round-trip data expressions.");
 
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         layer.textOpacity = functionExpression;
 
         std::map<float, float> innerStops { {18, 0xff} };
@@ -2559,7 +2559,7 @@
                               @"textTranslation should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"{1, 1}"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textTranslation = functionExpression;
 
         mbgl::style::IntervalStops<std::array<float, 2>> intervalStops = {{
@@ -2583,8 +2583,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textTranslation = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 
@@ -2603,7 +2603,7 @@
                               @"textTranslationAnchor should round-trip constant value expressions.");
 
         constantExpression = [NSExpression expressionWithFormat:@"'viewport'"];
-        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
+        NSExpression *functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:($zoomLevel, %@, %@)", constantExpression, @{@18: constantExpression}];
         layer.textTranslationAnchor = functionExpression;
 
         mbgl::style::IntervalStops<mbgl::style::TranslateAnchorType> intervalStops = {{
@@ -2627,8 +2627,8 @@
 
         functionExpression = [NSExpression expressionForKeyPath:@"bogus"];
         XCTAssertThrowsSpecificNamed(layer.textTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION(bogus, 'mgl_stepWithMinimum:stops:', %@, %@)", constantExpression, @{@18: constantExpression}];
-        functionExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{@10: functionExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_step:from:stops:(bogus, %@, %@)", constantExpression, @{@18: constantExpression}];
+        functionExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{@10: functionExpression}];
         XCTAssertThrowsSpecificNamed(layer.textTranslationAnchor = functionExpression, NSException, NSInvalidArgumentException, @"MGLSymbolLayer should raise an exception if a camera-data expression is applied to a property that does not support key paths to feature attributes.");
     }
 }
diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 5282469223..2a6708a69f 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -969,7 +969,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
                                       @12.0f: [UIColor greenColor],
                                       @14.0f: [UIColor blueColor]};
     waterLayer.fillColor = [NSExpression expressionWithFormat:
-                            @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                            @"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                             waterColorStops];
 
     NSDictionary *fillAntialiasedStops = @{@11: @YES,
@@ -978,7 +978,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
                                            @14: @NO,
                                            @15: @YES};
     waterLayer.fillAntialiased = [NSExpression expressionWithFormat:
-                                  @"FUNCTION($zoomLevel, 'mgl_stepWithMinimum:stops:', false, %@)",
+                                  @"mgl_step:from:stops:($zoomLevel, false, %@)",
                                   fillAntialiasedStops];
 }
 
@@ -991,7 +991,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
                                      @10: @15,
                                      @15: @30};
     NSExpression *lineWidthExpression = [NSExpression expressionWithFormat:
-                                         @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                                         @"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                          lineWidthStops];
     roadLayer.lineWidth = lineWidthExpression;
     roadLayer.lineGapWidth = lineWidthExpression;
@@ -1000,7 +1000,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
                                          @13: [UIColor yellowColor],
                                          @16: [UIColor cyanColor]};
     roadLayer.lineColor = [NSExpression expressionWithFormat:
-                           @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                           @"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                            roadLineColorStops];
 
     roadLayer.visible = YES;
@@ -1018,7 +1018,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
     NSDictionary *opacityStops = @{@20.0f: @1.0f,
                                    @5.0f: @0.0f};
     rasterLayer.rasterOpacity = [NSExpression expressionWithFormat:
-                                 @"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+                                 @"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                  opacityStops];
     [self.mapView.style addLayer:rasterLayer];
 }
diff --git a/platform/ios/docs/guides/For Style Authors.md b/platform/ios/docs/guides/For Style Authors.md
index 1f2803f3ec..7462112626 100644
--- a/platform/ios/docs/guides/For Style Authors.md
+++ b/platform/ios/docs/guides/For Style Authors.md
@@ -311,6 +311,11 @@ defined by the style specification.
 
 ### Expression operators
 
+Many expression operators defined in the style specification have corresponding
+symbols to be used with the `+[NSExpression expressionWithFormat:]`,
+`+[NSExpression expressionForFunction:arguments:]`, or
+`+[NSExpression expressionForFunction:selectorName:arguments:]` method:
+
 In style specification | Method, function, or predicate type | Format string syntax
 -----------------------|-------------------------------------|---------------------
 `array`                | |
@@ -320,15 +325,15 @@ In style specification | Method, function, or predicate type | Format string syn
 `string`               | |
 `to-boolean`           | `boolValue` |
 `to-color`             | |
-`to-number`            | `mgl_numberWithFallbackValues:` |
-`to-string`            | `stringValue` |
+`to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
+`to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
-`geometry-type`        | |
-`id`                   | |
-`properties`           | |
-`at`                   | |
+`geometry-type`        | |`$mgl_geometryType`
+`id`                   | |`$mgl_featureIdentifier`
+`properties`           | |`$mgl_featureProperties`
+`at`                   | `objectFrom:withIndex:` | `array[n]`
 `get`                  | `+[NSExpression expressionForKeyPath:]` | Key path
-`has`                  | |
+`has`                  | `mgl_does:have:` | `mgl_does:have:(self, 'key')`
 `length`               | `count:` | `count({1, 2, 2, 3, 4, 7, 9})`
 `!`                    | `NSNotPredicateType` | `NOT (p0 OR … OR pn)`
 `!=`                   | `NSNotEqualToPredicateOperatorType` | `key != value`
@@ -339,14 +344,14 @@ In style specification | Method, function, or predicate type | Format string syn
 `>=`                   | `NSGreaterThanOrEqualToPredicateOperatorType` | `key >= value`
 `all`                  | `NSAndPredicateType` | `p0 AND … AND pn`
 `any`                  | `NSOrPredicateType` | `p0 OR … OR pn`
-`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` | `TERNARY(condition, trueExpression, falseExpression)`
-`coalesce`             | |
-`match`                | |
-`interpolate`          | `mgl_interpolateWithCurveType:parameters:stops:` |
-`step`                 | `mgl_stepWithMinimum:stops:` |
-`let`                  | `mgl_expressionWithContext:` |
+`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` or `MGL_IF` | `TERNARY(1 = 2, YES, NO)` or `MGL_IF(1 = 2, YES, 2 = 2, YES, NO)`
+`coalesce`             | `mgl_coalesce:` | `mgl_coalesce({x, y, z})`
+`match`                | `MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')`
+`interpolate`          | `mgl_interpolate:withCurveType:parameters:stops:` |
+`step`                 | `mgl_step:withMinimum:stops:` |
+`let`                  | `mgl_expressionWithContext:` | `MGL_LET('ios', 11, 'macos', 10.13, $ios + $macos)`
 `var`                  | `+[NSExpression expressionForVariable:]` | `$variable`
-`concat`               | `stringByAppendingString:` |
+`concat`               | `mgl_join:` | `mgl_join({'Old', ' ', 'MacDonald'})`
 `downcase`             | `lowercase:` | `lowercase('DOWNTOWN')`
 `upcase`               | `uppercase:` | `uppercase('Elysian Fields')`
 `rgb`                  | `+[UIColor colorWithRed:green:blue:alpha:]` |
@@ -376,6 +381,9 @@ In style specification | Method, function, or predicate type | Format string syn
 `zoom`                 | | `$zoom`
 `heatmap-density`      | | `$heatmapDensity`
 
+For operators that have no corresponding `NSExpression` symbol, use the
+`MGL_FUNCTION()` format string syntax.
+
 ## Filtering sources
 
 You can filter a shape or vector source by setting the
diff --git a/platform/ios/docs/guides/Using Style Functions at Runtime.md b/platform/ios/docs/guides/Using Style Functions at Runtime.md
index 0b4e842e0e..7ac8a6aea5 100644
--- a/platform/ios/docs/guides/Using Style Functions at Runtime.md
+++ b/platform/ios/docs/guides/Using Style Functions at Runtime.md
@@ -66,7 +66,7 @@ let stops: [Float: UIColor] = [
 ]
 
 let layer = MGLCircleStyleLayer(identifier: "circles", source: source)
-layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+layer.circleColor = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(mag, 'linear', nil, %@)",
                                  stops)
 layer.circleRadius = NSExpression(forConstantValue: 10)
 mapView.style?.insertLayer(layer, below: symbolLayer)
@@ -92,7 +92,7 @@ let stops = [
     18: 18,
 ]
 
-layer.circleRadius = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.5, %@)",
+layer.circleRadius = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
                                   stops)
 ```
 
@@ -111,7 +111,7 @@ let stops: [Float: UIColor] = [
     10: .white,
 ]
 
-layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_stepWithMinimum:stops:', %@, %@)",
+layer.circleColor = NSExpression(format: "mgl_step:from:stops:(mag, %@, %@)",
                                  UIColor.green, stops)
 ```
 
diff --git a/platform/macos/app/MapDocument.m b/platform/macos/app/MapDocument.m
index 23bc652229..4d6c71584b 100644
--- a/platform/macos/app/MapDocument.m
+++ b/platform/macos/app/MapDocument.m
@@ -894,7 +894,7 @@ NS_ARRAY_OF(id <MGLAnnotation>) *MBXFlattenedShapes(NS_ARRAY_OF(id <MGLAnnotatio
     self.mapView.style.transition = transition;
 
     MGLStyleLayer *waterLayer = [self.mapView.style layerWithIdentifier:@"water"];
-    NSExpression *colorExpression = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{
+    NSExpression *colorExpression = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{
         @0.0: [NSColor redColor],
         @10.0: [NSColor yellowColor],
         @20.0: [NSColor blackColor],
@@ -927,7 +927,7 @@ NS_ARRAY_OF(id <MGLAnnotation>) *MBXFlattenedShapes(NS_ARRAY_OF(id <MGLAnnotatio
         theaterLayer.predicate = [NSPredicate predicateWithFormat:@"maki == 'theatre'"];
         theaterLayer.iconImageName = [NSExpression expressionForConstantValue:NSImageNameIChatTheaterTemplate];
         theaterLayer.iconScale = [NSExpression expressionForConstantValue:@2];
-        theaterLayer.iconColor = [NSExpression expressionWithFormat:@"FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)", @{
+        theaterLayer.iconColor = [NSExpression expressionWithFormat:@"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", @{
             @16.0: [NSColor redColor],
             @18.0: [NSColor yellowColor],
             @20.0: [NSColor blackColor],
diff --git a/platform/macos/docs/guides/For Style Authors.md b/platform/macos/docs/guides/For Style Authors.md
index 636cfa7eb7..d99d255273 100644
--- a/platform/macos/docs/guides/For Style Authors.md
+++ b/platform/macos/docs/guides/For Style Authors.md
@@ -304,6 +304,11 @@ iOS.
 
 ### Expression operators
 
+Many expression operators defined in the style specification have corresponding
+symbols to be used with the `+[NSExpression expressionWithFormat:]`,
+`+[NSExpression expressionForFunction:arguments:]`, or
+`+[NSExpression expressionForFunction:selectorName:arguments:]` method:
+
 In style specification | Method, function, or predicate type | Format string syntax
 -----------------------|-------------------------------------|---------------------
 `array`                | |
@@ -313,15 +318,15 @@ In style specification | Method, function, or predicate type | Format string syn
 `string`               | |
 `to-boolean`           | `boolValue` |
 `to-color`             | |
-`to-number`            | `mgl_numberWithFallbackValues:` |
-`to-string`            | `stringValue` |
+`to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
+`to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
-`geometry-type`        | |
-`id`                   | |
-`properties`           | |
-`at`                   | |
+`geometry-type`        | |`$mgl_geometryType`
+`id`                   | |`$mgl_featureIdentifier`
+`properties`           | |`$mgl_featureProperties`
+`at`                   | `objectFrom:withIndex:` | `array[n]`
 `get`                  | `+[NSExpression expressionForKeyPath:]` | Key path
-`has`                  | |
+`has`                  | `mgl_does:have:` | `mgl_does:have:(self, 'key')`
 `length`               | `count:` | `count({1, 2, 2, 3, 4, 7, 9})`
 `!`                    | `NSNotPredicateType` | `NOT (p0 OR … OR pn)`
 `!=`                   | `NSNotEqualToPredicateOperatorType` | `key != value`
@@ -332,14 +337,14 @@ In style specification | Method, function, or predicate type | Format string syn
 `>=`                   | `NSGreaterThanOrEqualToPredicateOperatorType` | `key >= value`
 `all`                  | `NSAndPredicateType` | `p0 AND … AND pn`
 `any`                  | `NSOrPredicateType` | `p0 OR … OR pn`
-`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` | `TERNARY(condition, trueExpression, falseExpression)`
-`coalesce`             | |
-`match`                | |
-`interpolate`          | `mgl_interpolateWithCurveType:parameters:stops:` |
-`step`                 | `mgl_stepWithMinimum:stops:` |
-`let`                  | `mgl_expressionWithContext:` |
+`case`                 | `+[NSExpression expressionForConditional:trueExpression:falseExpression:]` or `MGL_IF` | `TERNARY(1 = 2, YES, NO)` or `MGL_IF(1 = 2, YES, 2 = 2, YES, NO)`
+`coalesce`             | `mgl_coalesce:` | `mgl_coalesce({x, y, z})`
+`match`                | `MGL_MATCH` | `MGL_MATCH(x, 0, 'zero match', 1, 'one match', 'two match', 'default')`
+`interpolate`          | `mgl_interpolate:withCurveType:parameters:stops:` |
+`step`                 | `mgl_step:withMinimum:stops:` |
+`let`                  | `mgl_expressionWithContext:` | `MGL_LET('ios', 11, 'macos', 10.13, $ios + $macos)`
 `var`                  | `+[NSExpression expressionForVariable:]` | `$variable`
-`concat`               | `stringByAppendingString:` |
+`concat`               | `mgl_join:` | `mgl_join({'Old', ' ', 'MacDonald'})`
 `downcase`             | `lowercase:` | `lowercase('DOWNTOWN')`
 `upcase`               | `uppercase:` | `uppercase('Elysian Fields')`
 `rgb`                  | `+[NSColor colorWithCalibratedRed:green:blue:alpha:]` |
@@ -369,6 +374,9 @@ In style specification | Method, function, or predicate type | Format string syn
 `zoom`                 | | `$zoom`
 `heatmap-density`      | | `$heatmapDensity`
 
+For operators that have no corresponding `NSExpression` symbol, use the
+`MGL_FUNCTION()` format string syntax.
+
 ## Filtering sources
 
 You can filter a shape or vector source by setting the
diff --git a/platform/macos/docs/guides/Using Style Functions at Runtime.md b/platform/macos/docs/guides/Using Style Functions at Runtime.md
index 4e854aaaa0..e87cd00185 100644
--- a/platform/macos/docs/guides/Using Style Functions at Runtime.md
+++ b/platform/macos/docs/guides/Using Style Functions at Runtime.md
@@ -66,7 +66,7 @@ let stops: [Float: NSColor] = [
 ]
 
 let layer = MGLCircleStyleLayer(identifier: "circles", source: source)
-layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_interpolateWithCurveType:parameters:stops:', 'linear', nil, %@)",
+layer.circleColor = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:(mag, 'linear', nil, %@)",
                                  stops)
 layer.circleRadius = NSExpression(forConstantValue: 10)
 mapView.style?.insertLayer(layer, below: symbolLayer)
@@ -92,7 +92,7 @@ let stops = [
     18: 18,
 ]
 
-layer.circleRadius = NSExpression(format: "FUNCTION($zoomLevel, 'mgl_interpolateWithCurveType:parameters:stops:', 'exponential', 1.5, %@)",
+layer.circleRadius = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
                                   stops)
 ```
 
@@ -111,7 +111,7 @@ let stops: [Float: NSColor] = [
     10: .white,
 ]
 
-layer.circleColor = NSExpression(format: "FUNCTION(mag, 'mgl_stepWithMinimum:stops:', %@, %@)",
+layer.circleColor = NSExpression(format: "mgl_step:from:stops:(mag, %@, %@)",
                                  NSColor.green, stops)
 ```