On Tue, May 17, 2005 at 01:13:17PM +0200, Jens Blanck wrote: > > > How would I introduce number classes that are extended with plus and > > > minus infinity? I'd like to have polymorphism over these new classes, > > > something like a signature > > > > > > f :: (Real a, Extended a b) => b -> b > > > > > > which clearly is not part of the current syntax, but I hope you get > > > the picture. What are the elegant ways of doing this? > > > > How about > > f :: Real a => Extended a -> Extended a > > Not quite what I had in mind. I'd like to have extended integers and > extended rationals, and possibly extended dyadic numbers. So I can't > have just a single type ExtendedRational (unless I'm prepared to do > some ugly coersing).
You're missing the point. Try:
> data Extended a = PlusInf | NegInf | Finite a
Peace,
Dylan
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