Use OPTIONS rather than OPTIONS_GHC for pragmas

[ghc-hetmet.git] / compiler / utils / Maybes.lhs

diff --git a/compiler/utils/Maybes.lhs b/compiler/utils/Maybes.lhs
index 3c9bd69..4e4726a 100644 (file)
--- a/compiler/utils/Maybes.lhs
+++ b/compiler/utils/Maybes.lhs
@@ -1,14 +1,21 @@
 %
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-\section[Maybes]{The `Maybe' types and associated utility functions}
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/CodingStyle#Warnings
+-- for details
+
 module Maybes (
-       module Maybe,           -- Re-export all of Maybe
+       module Data.Maybe,      -- Re-export all of Maybe
 
        MaybeErr(..),   -- Instance of Monad
-       failME,
+       failME, isSuccess,
 
        orElse, 
        mapCatMaybes,
@@ -17,13 +24,12 @@ module Maybes (
        expectJust,
        maybeToBool,
 
-       thenMaybe, seqMaybe, returnMaybe, failMaybe
+       thenMaybe, seqMaybe, returnMaybe, failMaybe, fmapMMaybe
     ) where
 
 #include "HsVersions.h"
 
-import Maybe
-
+import Data.Maybe
 
 infixr 4 `orElse`
 \end{code}
@@ -101,6 +107,11 @@ 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}
 
 
@@ -118,6 +129,10 @@ instance Monad (MaybeErr err) where
   Succeeded v >>= k = k v
   Failed e    >>= k = Failed e
 
+isSuccess :: MaybeErr err val -> Bool
+isSuccess (Succeeded {}) = True
+isSuccess (Failed {})    = False
+
 failME :: err -> MaybeErr err val
 failME e = Failed e
 \end{code}