Variadic compose function?

Question

I\'m trying to write a variadic function composition function. Which is basically the (.) except that the second argument function is variadic. This should allo

Answer 1

It is possible to type-hack it into working with polymorphic functions:

{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses,
  IncoherentInstances, UndecidableInstances,
  FunctionalDependencies, TypeFamilies,
  NoMonomorphismRestriction #-}


class Comp a b c | a b -> c where
    (...) :: a -> b -> c

instance (a ~ c, r ~ b) => Comp (a -> b) c r where
    f ... g = f g

instance (Comp (a -> b) d r1, r ~ (c -> r1)) => Comp (a -> b) (c -> d) r where
    f ... g = \c -> f ... g c

t1 = map even ... zipWith (+)
t2 = map even ... zipWith
t3 = (+1) ... foldr

But I doubt you can avoid IncoherentInstances