broke up Utility

1 files changed, 26 insertions, 0 deletions

diff --git a/Utility/Monad.hs b/Utility/Monad.hs
new file mode 100644
index 000000000..9523e1716
--- /dev/null
+++ b/Utility/Monad.hs
@@ -0,0 +1,26 @@
+{- monadic stuff
+ -
+ - Copyright 2010-2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Utility.Monad where
+
+import Data.Maybe
+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 _ [] = return Nothing
+firstM p (x:xs) = do
+	q <- p x
+	if q
+		then return (Just x)
+		else firstM p xs
+
+{- Returns true if any value in the list satisfies the preducate,
+ - stopping once one is found. -}
+anyM :: (Monad m) => (a -> m Bool) -> [a] -> m Bool
+anyM p = liftM isJust . firstM p