'idiomatic' Haskell type inequality

Question

(edited from previous question where I thought code below doesn\'t work)

I wish to implement a haskell function f that has a restriction such that its 2 parameters m

Answer 1

With new features being added to GHC, you'll be able to write:

{-# LANGUAGE DataKinds, PolyKinds, TypeFamilies #-}

type family Equal (a :: k) (b :: k) :: Bool
type instance where
   Equal a a = True
   Equal a b = False