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authorGravatar Joey Hess <joey@kitenet.net>2012-01-21 02:24:12 -0400
committerGravatar Joey Hess <joey@kitenet.net>2012-01-21 02:49:32 -0400
commit183bdacca219065e6a888385e3bf309708e827ec (patch)
tree6ee1c6ba8b75de8b182fd969b612a8557f72360c /Utility/Monad.hs
parenteb9001044f3db682236d1007aded58f47109d6a6 (diff)
treak
Diffstat (limited to 'Utility/Monad.hs')
-rw-r--r--Utility/Monad.hs10
1 files changed, 5 insertions, 5 deletions
diff --git a/Utility/Monad.hs b/Utility/Monad.hs
index 95964361e..28aa33ee8 100644
--- a/Utility/Monad.hs
+++ b/Utility/Monad.hs
@@ -12,7 +12,7 @@ import Control.Monad (liftM)
{- Return the first value from a list, if any, satisfying the given
- predicate -}
-firstM :: (Monad m) => (a -> m Bool) -> [a] -> m (Maybe a)
+firstM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)
firstM _ [] = return Nothing
firstM p (x:xs) = do
q <- p x
@@ -22,20 +22,20 @@ firstM p (x:xs) = do
{- Returns true if any value in the list satisfies the predicate,
- stopping once one is found. -}
-anyM :: (Monad m) => (a -> m Bool) -> [a] -> m Bool
+anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool
anyM p = liftM isJust . firstM p
{- Runs an action on values from a list until it succeeds. -}
-untilTrue :: (Monad m) => [a] -> (a -> m Bool) -> m Bool
+untilTrue :: Monad m => [a] -> (a -> m Bool) -> m Bool
untilTrue = flip anyM
{- Runs an action, passing its value to an observer before returning it. -}
-observe :: (Monad m) => (a -> m b) -> m a -> m a
+observe :: Monad m => (a -> m b) -> m a -> m a
observe observer a = do
r <- a
_ <- observer r
return r
{- b `after` a runs first a, then b, and returns the value of a -}
-after :: (Monad m) => m b -> m a -> m a
+after :: Monad m => m b -> m a -> m a
after = observe . const