diff options
| -rw-r--r-- | libraries/base/Data/Maybe.hs | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/libraries/base/Data/Maybe.hs b/libraries/base/Data/Maybe.hs index d8aad53b9e..5f5d5ac910 100644 --- a/libraries/base/Data/Maybe.hs +++ b/libraries/base/Data/Maybe.hs @@ -228,9 +228,12 @@ maybeToList (Just x) = [x] -- >>> maybeToList $ listToMaybe [1,2,3] -- [1] -- -listToMaybe :: [a] -> Maybe a -listToMaybe [] = Nothing -listToMaybe (a:_) = Just a +listToMaybe :: [a] -> Maybe a +listToMaybe = foldr (const . Just) Nothing +{-# INLINE listToMaybe #-} +-- We define listToMaybe using foldr so that it can fuse via the foldr/build +-- rule. See #14387 + -- | The 'catMaybes' function takes a list of 'Maybe's and returns -- a list of all the 'Just' values. |