broke up Utility

This commit is contained in:
Joey Hess 2011-10-16 00:31:25 -04:00
parent 91366c896d
commit 23f2a12816
16 changed files with 126 additions and 112 deletions

26
Utility/Monad.hs Normal file
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{- 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