, MonadFix(..)
, MonadIO(..)
+
+ , ID, runID
, liftIO1, liftIO2, liftIO3, liftIO4
, mapSndM
, concatMapM
, mapMaybeM
+ , fmapMaybeM, fmapEitherM
, anyM, allM
, foldlM, foldlM_, foldrM
, maybeMapM
) where
+import Outputable
+
----------------------------------------------------------------------------------------
-- Detection of available libraries
----------------------------------------------------------------------------------------
import Control.Monad.Fix
----------------------------------------------------------------------------------------
+-- The ID monad
+----------------------------------------------------------------------------------------
+
+newtype ID a = ID a
+instance Monad ID where
+ return x = ID x
+ (ID x) >>= f = f x
+ _ >> y = y
+ fail s = panic s
+
+runID :: ID a -> a
+runID (ID x) = x
+
+----------------------------------------------------------------------------------------
-- MTL
----------------------------------------------------------------------------------------
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