infinite (fractional) precision

[Ashley Yakeley]

At 2002-10-10 01:29, Ketil Z. Malde wrote:

>I realize it's probably far from trivial, e.g. comparing two equal
>numbers could easily not terminate, and memory exhaustion would
>probably arise in many other cases.

I considered doing something very like this for real (computable) 
numbers, but because I couldn't properly make the type an instance of Eq, 
I left it. Actually it was worse than that. Suppose I'm adding two 
numbers, both of which are actually 1, but I don't know that:

 1.000000000.... +
 0.999999999....

The trouble is, as far as I know with a finite number of digits, the 
answer might be

 1.9999999999937425

or it might be

 2.0000000000013565

...so I can't actually generate any digits at all. So I can't even make 
the type an instance of my Additive class. Not very useful...

-- 
Ashley Yakeley, Seattle WA