X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Futils%2FMaybes.lhs;h=af7d3f6ca51c3e3fecfc88dcf6a26426702d969e;hb=8100c58a929d993d2dd7022412ed6113cf97fba7;hp=7d1fa4e306957a69621b81c695c7b06a4afb65d0;hpb=046ee54f048ddd721dcee41916d6a6f68db3b15b;p=ghc-hetmet.git

diff --git a/compiler/utils/Maybes.lhs b/compiler/utils/Maybes.lhs
index 7d1fa4e..af7d3f6 100644
--- a/compiler/utils/Maybes.lhs
+++ b/compiler/utils/Maybes.lhs
@@ -17,7 +17,7 @@ module Maybes (
 	expectJust,
 	maybeToBool,
 
-	thenMaybe, seqMaybe, returnMaybe, failMaybe
+	thenMaybe, seqMaybe, returnMaybe, failMaybe, fmapMMaybe
     ) where
 
 #include "HsVersions.h"
@@ -100,6 +100,11 @@ failMaybe = Nothing
 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}