Combinator birds in Clojure

Well, here's the type signatures for each:

    pure (== return) :: (Applicative f) => a -> f a
    <$> (== fmap) :: (Functor f) => (a -> b) -> (f a -> f b)
    join :: (Monad m) => m (m a) -> m a

All of these are polymorphic, and example in the case of lists would be

    pure x = [x]
    odd <$> [1,2,3] == [True, False, True]
    join [[1,2], [3], [4,5]] = [1,2,3,4,5]