Natural transformation typeclass

NT.hs

{-# LANGUAGE MultiParamTypeClasses, TypeOperators #-}

import Data.Maybe (maybeToList)

class (~>) m n where
  nt :: m x -> n x

instance (~>) Maybe [] where
  nt = maybeToList

doTheThing :: m ~> n => m x -> n x
doTheThing = nt

x :: [Int]
x = doTheThing $ Just 10

NT.idr

infixl 3 ~>

interface (~>) (m : Type -> Type) (n : Type -> Type) where
  nt : m x -> n x

(~>) Maybe List where
  nt = toList

doTheThing : m ~> n => m x -> n x
doTheThing = nt

x : List Int
x = doTheThing $ Just 10