{-# LANGUAGE TypeFamilies #-}
module M where

import Data.Kind (Type)

class TupArgs tup where
  type TupFun tup r :: Type
  applyTupFun :: TupFun tup r -> tup -> r

instance TupArgs () where
  type TupFun () r = r
  applyTupFun x _ = x

instance TupArgs (a, b) where
  type TupFun (a, b) r = a -> b -> r
  applyTupFun f (x, y) = f x y

instance TupArgs (a, b, c) where
  type TupFun (a, b, c) r = a -> b -> c -> r
  applyTupFun f (x, y, z) = f x y z