CPS, Continuation Monad, and Writer Monad の例。 part :: (a -> Bool) -> [a] -> [a] part p l = let f [] z = z f (x:xs) z = if p x then x : f xs z else f xs (z++[x]) in f l []をいろいろに書いてみる*1。 *1:[id:yokoyamatetsuo:20050219#p5]より