Refactor SrcLoc and SrcSpan

[ghc-hetmet.git] / compiler / utils / MonadUtils.hs

diff --git a/compiler/utils/MonadUtils.hs b/compiler/utils/MonadUtils.hs
index 5e01a22..75a88df 100644 (file)
--- a/compiler/utils/MonadUtils.hs
+++ b/compiler/utils/MonadUtils.hs
@@ -19,6 +19,7 @@ module MonadUtils
         , mapSndM
         , concatMapM
         , mapMaybeM
+       , fmapMaybeM, fmapEitherM
         , anyM, allM
         , foldlM, foldlM_, foldrM
         , maybeMapM
@@ -26,16 +27,16 @@ module MonadUtils
 
 import Outputable 
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- Detection of available libraries
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 -- we don't depend on MTL for now
 #define HAVE_MTL 0
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- Imports
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 import Maybes
 
@@ -46,9 +47,9 @@ import Control.Monad.Trans
 import Control.Monad
 import Control.Monad.Fix
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- The ID monad
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 newtype ID a = ID a
 instance Monad ID where
@@ -60,9 +61,9 @@ instance Monad ID where
 runID :: ID a -> a
 runID (ID x) = x
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- MTL
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 #if !HAVE_MTL
 
@@ -72,10 +73,10 @@ class Monad m => MonadIO m where
 instance MonadIO IO where liftIO = id
 #endif
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- Lift combinators
 --  These are used throughout the compiler
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 -- | Lift an 'IO' operation with 1 argument into another monad
 liftIO1 :: MonadIO m => (a -> IO b) -> a -> m b
@@ -93,10 +94,10 @@ liftIO3 = ((.).((.).(.))) liftIO
 liftIO4 :: MonadIO m => (a -> b -> c -> d -> IO e) -> a -> b -> c -> d -> m e
 liftIO4 = (((.).(.)).((.).(.))) liftIO
 
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 -- Common functions
 --  These are used throughout the compiler
-----------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 zipWith3M :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m [d]
 zipWith3M _ []     _      _      = return []
@@ -148,6 +149,16 @@ concatMapM f xs = liftM concat (mapM f xs)
 mapMaybeM :: (Monad m) => (a -> m (Maybe b)) -> [a] -> m [b]
 mapMaybeM f = liftM catMaybes . mapM f
 
+-- | Monadic version of fmap
+fmapMaybeM :: (Monad m) => (a -> m b) -> Maybe a -> m (Maybe b)
+fmapMaybeM _ Nothing  = return Nothing
+fmapMaybeM f (Just x) = f x >>= (return . Just)
+
+-- | Monadic version of fmap
+fmapEitherM :: Monad m => (a -> m b) -> (c -> m d) -> Either a c -> m (Either b d)
+fmapEitherM fl _ (Left  a) = fl a >>= (return . Left)
+fmapEitherM _ fr (Right b) = fr b >>= (return . Right)
+
 -- | Monadic version of 'any', aborts the computation at the first @True@ value
 anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool
 anyM _ []     = return False