{-# LANGUAGE NoImplicitPrelude #-}
import List
import Functor --for test

class (Functor f) => Applicative f where
    pure :: a -> f a
    (<*>) :: f (a -> b) -> f a -> f b

--Test. Works for me.
instance Applicative List where
    pure x = (Cons x Nil)
    (Cons f Nil) <*> (Cons x Nil) = (Cons (f x) Nil)
    (Cons f l) <*> (Cons x Nil) = (Cons (f x) (l <*> x))
    (Cons f Nil) <*> (Cons x l) = (Cons (f x) (f <*> l))
    (Cons f l1) <*> (Cons x l2) = (Cons (f x) (Cons (l1 <*> x) (Cons (f <*> l2) (l1 <*> l2))))