module Control.Monad.Extensions (satisfiesM,if') where

import Control.Applicative (Applicative,liftA3)

satisfiesM :: Monad m => (a -> Bool) -> m a -> m a
satisfiesM p x = x >>= if' p return (const (satisfiesM p x))

if' :: Applicative f => f Bool -> f a -> f a -> f a
if' = liftA3 (\ c t e -> if c then t else e)