flip.hs

flip' :: (a -> b -> c) -> (b -> a -> c)
flip' f = g
    where g x y = f y x

flip'' :: (a -> b -> c) -> b -> a -> c
-- flip'' :: a -> b -> c -> b -> a -> c -- このように書くとエラー
flip'' f x y = f y x

main = do
    print $ flip' map [1..5] (* 2)
    print $ flip'' map [1..5] (* 3)
    print $ flip'' zip [1..5] "hello"
    print $ flip'' zip "hello" [1..5]