tk n = map snd . box n . zip [1..]
tendríamos:
tk n = (map snd) . (box n) . (zip [1..])
por lo que nos quedaría:
tk n xs = map snd (box n (zip [1..] xs))
tk n = map snd . box n . zip [1..]
tk n = (map snd) . (box n) . (zip [1..])
tk n xs = map snd (box n (zip [1..] xs))