On Tue, 27 Nov 2007, Bit Connor wrote:
Actually, IEEE numbers are designed in such a way, that if you interpret their bits as integer number, then 'succ' leads you to the next larger representable number. Thus you only have to cast from Float or Double to Int32 or Int64 respectively, call enumFromTo, then cast back to Float or Double, respectively. :-]
How do you cast from Float to Int32(or Word32), and back again? I couldn't find an appropriate function. Only thing I can see is going through the Storable interface, but that seems cumbersome and I imagine slow.
As Don pointed out correctly I'm evil. Storable is a fine way, since it makes a hack look like a hack. Or you might use castSTUArray.
Also, a related question: How do you convert from Float -> Double, and the reverse? Only thing I could find is (fromRational . toRational) which I also imagine to be slow, and I also wonder about accuracy.
Rational keeps full precision. Performance - I don't know, maybe it's fused away? When I started with Haskell I regularly needed conversion between Float and Double. I don't know why. I haven't needed it for a long time now.