Re: Re[6]: All Monads are Functors

On Tue, Aug 15, 2006 at 10:34:39PM +0100, Jon Fairbairn wrote:

It seems obvious to me that we always use an external definition if one exists, so I suppose the problem is knowing whether an external instance exists -- so this proposal would rely on doing something about scoping for instances, I suppose.

The problem is you can't have working code change its behavior because of a module import (other than failing), say, by bringing an instance into scope that wasn't before. There is no way to have a monad instance 'automatically' declare a functor instance without changing what the mo instance looks like somehow which would be a backwards incompatable change. John -- John Meacham - ⑆repetae.net⑆john⑈