On 19 March 2012 17:58, Chris Smith <cdsmith@gmail.com> wrote:

On Mar 19, 2012 11:40 AM, "Ozgur Akgun" <ozgurakgun@gmail.com> 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.

Thanks for catching this one, you are absolutely correct. I was carried away by the original post using "Float -> Float" for the example functions.

Cheers,

Ozgur