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

Chris Smith cdsmith at gmail.com
Mon Mar 19 18:58:48 CET 2012

On Mar 19, 2012 11:40 AM, "Ozgur Akgun" <ozgurakgun at 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.

Chris Smith
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