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fix non-GHC-specific variant of FastTypes
[ghc-hetmet.git]
/
compiler
/
utils
/
Maybes.lhs
diff --git
a/compiler/utils/Maybes.lhs
b/compiler/utils/Maybes.lhs
index
7d1fa4e
..
af7d3f6
100644
(file)
--- a/
compiler/utils/Maybes.lhs
+++ b/
compiler/utils/Maybes.lhs
@@
-17,7
+17,7
@@
module Maybes (
expectJust,
maybeToBool,
expectJust,
maybeToBool,
- thenMaybe, seqMaybe, returnMaybe, failMaybe
+ thenMaybe, seqMaybe, returnMaybe, failMaybe, fmapMMaybe
) where
#include "HsVersions.h"
) where
#include "HsVersions.h"
@@
-100,6
+100,11
@@
failMaybe = Nothing
orElse :: Maybe a -> a -> a
(Just x) `orElse` y = x
Nothing `orElse` y = y
orElse :: Maybe a -> a -> a
(Just x) `orElse` y = x
Nothing `orElse` y = y
+
+fmapMMaybe :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b)
+fmapMMaybe f Nothing = return Nothing
+fmapMMaybe f (Just x) = f x >>= \x' -> return (Just x')
+
\end{code}
\end{code}