Re: Double -> CDouble, realToFrac doesn't work

On Fri, Nov 05, 2004 at 10:53:36AM +0100, Marcin 'Qrczak' Kowalczyk wrote:

ross@soi.city.ac.uk writes:

...

[The proposal is to add 0:%0, 1:%0 and -1:%0 to Rational.]

Changing Rational from meaning rational numbers would also be bad. I'd prefer to redefine realToFrac to go through a new type that is the union of Rational and these values.

It's not enough if you care about preserving -0.0.

True, and denormalized values (whatever they are).

Instead of materializing variants, the function could check isInfinite etc. - except that these functions are in RealFloat class, not available for arbitrary Real numbers.

But isn't that fatal? We're stuck with the type realToFrac :: (Real a, Fractional b) => a -> b All we can change is its specification.