Annotate the non-total function in Data.Foldable as such

1 files changed, 20 insertions, 0 deletions

diff --git a/libraries/base/Data/Foldable.hs b/libraries/base/Data/Foldable.hs
index 3624a36b15..7c1fcd7ffb 100644
--- a/libraries/base/Data/Foldable.hs
+++ b/libraries/base/Data/Foldable.hs
@@ -215,6 +215,8 @@ class Foldable t where
     -- | A variant of 'foldr' that has no base case,
     -- and thus may only be applied to non-empty structures.
     --
+    -- ⚠️ This function is non-total and will raise a runtime exception if the structure happens to be empty.
+    --
     -- @'foldr1' f = 'List.foldr1' f . 'toList'@
     foldr1 :: (a -> a -> a) -> t a -> a
     foldr1 f xs = fromMaybe (errorWithoutStackTrace "foldr1: empty structure")
@@ -227,6 +229,8 @@ class Foldable t where
     -- | A variant of 'foldl' that has no base case,
     -- and thus may only be applied to non-empty structures.
     --
+    -- ⚠️ This function is non-total and will raise a runtime exception if the structure happens to be empty.
+    --
     -- @'foldl1' f = 'List.foldl1' f . 'toList'@
     foldl1 :: (a -> a -> a) -> t a -> a
     foldl1 f xs = fromMaybe (errorWithoutStackTrace "foldl1: empty structure")
@@ -267,6 +271,14 @@ class Foldable t where
 
     -- | The largest element of a non-empty structure.
     --
+    -- ⚠️ This function is non-total and will raise a runtime exception if the structure happens to be empty.
+    --
+    -- === __Examples__
+    -- >>> maximum [1..10]
+    -- 10
+    -- >>> maximum []
+    -- *** Exception: Prelude.maximum: empty list
+    --
     -- @since 4.8.0.0
     maximum :: forall a . Ord a => t a -> a
     maximum = fromMaybe (errorWithoutStackTrace "maximum: empty structure") .
@@ -274,6 +286,14 @@ class Foldable t where
 
     -- | The least element of a non-empty structure.
     --
+    -- ⚠️ This function is non-total and will raise a runtime exception if the structure happens to be empty
+    --
+    -- === __Examples__
+    -- >>> minimum [1..10]
+    -- 1
+    -- >>> minimum []
+    -- *** Exception: Prelude.minimum: empty list
+    --
     -- @since 4.8.0.0
     minimum :: forall a . Ord a => t a -> a
     minimum = fromMaybe (errorWithoutStackTrace "minimum: empty structure") .