Haskell' - class aliases

Wolfgang Jeltsch g9ks157k at acme.softbase.org
Thu Apr 24 14:51:12 EDT 2008

Am Mittwoch, 23. April 2008 06:18 schrieb John Meacham:
> On Tue, Apr 22, 2008 at 08:33:53AM +0100, Simon Peyton-Jones wrote:
> > Is this the most up-to-date description of the proposal?
> >         http://repetae.net/recent/out/classalias.html
> There were a few changes proposed in the discussion that followed my
> announcement that I wanted to make. The one I can remember now is
> getting rid of the 'alias' keyword since the equals sign unabiguously
> identifies it as an alias. I will dig through the archive to find the
> others..
> > I've just had another look, which threw up quite a few questions in my
> > mind.   I wonder what would be a good list to discuss it.  Maybe this
> > one is not bad, because it has people interested in Haskell
> > innovation, regardless of whether it's a live Haskell' candidate?
> Sounds good to me.
>         John

By the way, what are your current thoughts about your supertyping proposal.  
At least, on <http://repetae.net/recent/out/supertyping.html> you say:

> This functionality becomes even more necessary when faced with binary-only
> libraries and standard language features which cannot be easily rewritten or
> overridden without great effort.  

This seems to be an advantage compared to the class alias library.  On the 
other hand, it looks a bit weird to me that you can express a class relation 
in two different ways: A t => B t and B t <= A t.

Best wishes,

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