Re: [Haskell-cafe] Are there arithmetic composition of functions?

On Mar 19, 2012 11:40 AM, "Ozgur Akgun" wrote:

{-# LANGUAGE FlexibleInstances #-}

instance Num a => Num (a -> a) where

You don't want (a -> a) there. You want (b -> a). There is nothing about this that requires functions to come from a numeric type, much less the same one. -- Chris Smith