diff options
Diffstat (limited to 'compiler/GHC/Data/Maybe.hs')
| -rw-r--r-- | compiler/GHC/Data/Maybe.hs | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/compiler/GHC/Data/Maybe.hs b/compiler/GHC/Data/Maybe.hs index 3163829f75..215a2a0d6f 100644 --- a/compiler/GHC/Data/Maybe.hs +++ b/compiler/GHC/Data/Maybe.hs @@ -34,6 +34,7 @@ import Control.Exception (SomeException(..)) import Data.Maybe import Data.Foldable ( foldlM ) import GHC.Utils.Misc (HasCallStack) +import Data.List.NonEmpty ( NonEmpty ) infixr 4 `orElse` @@ -50,8 +51,10 @@ firstJust a b = firstJusts [a, b] -- | Takes a list of @Maybes@ and returns the first @Just@ if there is one, or -- @Nothing@ otherwise. -firstJusts :: [Maybe a] -> Maybe a +firstJusts :: Foldable f => f (Maybe a) -> Maybe a firstJusts = msum +{-# SPECIALISE firstJusts :: [Maybe a] -> Maybe a #-} +{-# SPECIALISE firstJusts :: NonEmpty (Maybe a) -> Maybe a #-} -- | Takes computations returnings @Maybes@; tries each one in order. -- The first one to return a @Just@ wins. Returns @Nothing@ if all computations |