1 files changed, 9 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/dsl.cpp b/src/mbgl/style/expression/dsl.cpp
index 2298bdf8d3..5532e0a520 100644
--- a/src/mbgl/style/expression/dsl.cpp
+++ b/src/mbgl/style/expression/dsl.cpp
@@ -1,4 +1,5 @@
 #include <mbgl/style/expression/dsl.hpp>
+#include <mbgl/style/expression/error.hpp>
 #include <mbgl/style/expression/literal.hpp>
 #include <mbgl/style/expression/assertion.hpp>
 #include <mbgl/style/expression/coercion.hpp>
@@ -28,6 +29,10 @@ static std::unique_ptr<Expression> compound(const char* op, Args... args) {
     return std::move(*result);
 }
 
+std::unique_ptr<Expression> error(std::string message) {
+    return std::make_unique<Error>(std::move(message));
+}
+
 std::unique_ptr<Expression> literal(const char* value) {
     return literal(std::string(value));
 }
@@ -60,6 +65,10 @@ std::unique_ptr<Expression> string(std::unique_ptr<Expression> value) {
     return std::make_unique<Assertion>(type::String, vec(std::move(value)));
 }
 
+std::unique_ptr<Expression> boolean(std::unique_ptr<Expression> value) {
+    return std::make_unique<Assertion>(type::Boolean, vec(std::move(value)));
+}
+
 std::unique_ptr<Expression> toColor(const char* value) {
     return toColor(literal(value));
 }