17 May
2005
17 May
'05
7:13 a.m.
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
Double and Float already include -Infinity and +Infinity:
Prelude> -(1/0) :: Double -Infinity
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). Jens