MultiFilters.hs

module MultiFilters where

import Control.Applicative ((<$>))

(.:) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
a .: b = (a .) . b

juxt :: [a -> b] -> a -> [b]
juxt = sequence

juxtReduce :: ([b] -> c) -> [a -> b] -> a -> c
juxtReduce = (.: juxt)

filterAll :: [a -> Bool] -> [a] -> [a]
filterAll = filter . juxtReduce and

filterAny :: [a -> Bool] -> [a] -> [a]
filterAny = filter . juxtReduce or

divisibleBy :: Integral a => a -> a -> Bool
divisibleBy x y = y `mod` x == 0

example = filterAll (not .: divisibleBy <$> [2,3,5]) [1..20]