Lennart Augustsson <lennart <at> augustsson.net> writes: > On Mon, Oct 27 2008, Bart Massey <bart <at> cs.pdx.edu> wrote: > > I think given that the Haskell 98 Report is pretty > > explicit about the behavior of round, we're stuck with > > it, but I don't like it. It's yet another tiny > > impediment to Haskell newbies, as demonstrated by the > > original post. > > You're assuming newbies from a bad educational system that > hasn't taught them how to round properly. :)
Naw. :-) I'm just saying that the name "round" is unfortunate, since there's no single universally accepted mathematical definition for it. For this reason many programming languages either don't provide it or provide a different version. The names "roundHalfUp" and "roundHalfEven" are much better: they each correspond to a well-known mathematical function that is codified in an IEEE standards document. If it were up to me, I'd deprecate round in Haskell' and make the documentation point to these other rounding functions. Our solution in Nickle (http://nickle.org), BTW, was to provide floating point with user-settable mantissa precision and a default precision of 256 bits. For all practical purposes we know of, this makes worrying about the edge cases for rounding pointless. Kahan has a nice paper on this that I can't find right now. Of course, this solution also makes FP computation creepingly slow, and exposes users to occasional bugs in our FP math library... :-) Bart Massey bart <at> cs.pdx.edu _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
