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Print unfoldings on lambda-bound variables
[ghc-hetmet.git]
/
compiler
/
utils
/
Maybes.lhs
diff --git
a/compiler/utils/Maybes.lhs
b/compiler/utils/Maybes.lhs
index
8a6a5f4
..
1f443db
100644
(file)
--- a/
compiler/utils/Maybes.lhs
+++ b/
compiler/utils/Maybes.lhs
@@
-10,6
+10,7
@@
module Maybes (
MaybeErr(..), -- Instance of Monad
failME, isSuccess,
MaybeErr(..), -- Instance of Monad
failME, isSuccess,
+ fmapM_maybe,
orElse,
mapCatMaybes,
allMaybes,
orElse,
mapCatMaybes,
allMaybes,
@@
-74,6
+75,14
@@
orElse :: Maybe a -> a -> a
Nothing `orElse` y = y
\end{code}
Nothing `orElse` y = y
\end{code}
+\begin{code}
+fmapM_maybe :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b)
+fmapM_maybe _ Nothing = return Nothing
+fmapM_maybe f (Just x) = do
+ x' <- f x
+ return $ Just x'
+\end{code}
+
%************************************************************************
%* *
\subsection[MaybeT type]{The @MaybeT@ monad transformer}
%************************************************************************
%* *
\subsection[MaybeT type]{The @MaybeT@ monad transformer}