Proposal: Remove Show and Eq superclasses of Num

Ian Lynagh igloo at
Fri Sep 16 03:41:34 CEST 2011

On Fri, Sep 16, 2011 at 12:47:18AM +0100, Paterson, Ross wrote:
> Ian Lynagh writes:
> > I would like to propose that we remove the Show and Eq superclasses from
> > Num, i.e. change
> >     class  (Eq a, Show a) => Num a  where
> >         [...]
> > to
> >     class  Num a  where
> >         [...]
> This will break client code, but will not fix other defects of Num,

It doesn't solve everything, but I hope we can agree it is an
incremental step in the right direction. I don't think a revolutionary
change fixing all the issues is feasible. This particular blemish was
already being described as "largely historical" more than a decade ago:


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