[racket-dev] `math' compilation time !!!

Yes, you're right. Sorry for that confusion. I don't have that confusion
with positive? and +0.0, after all!

Robby


On Fri, Mar 1, 2013 at 10:50 AM, Eric Dobson <eric.n.dobson at gmail.com>wrote:

> Why is Nonnegative-Real not suggestive of the right thing? To me that
> means (and/c real? (not/c (lambda (x) (< x 0)))) which is exactly what
> it is.
>
> I think the confusing part is that -0.0 has a minus sign in front
> which means that you think it is negative, but this isn't true.
>
> On Fri, Mar 1, 2013 at 8:31 AM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
> > Is there perhaps a more suggestive name? (Not that I'm coming up with
> > one...)
> >
> > Robby
> >
> >
> > On Fri, Mar 1, 2013 at 10:22 AM, Vincent St-Amour <stamourv at ccs.neu.edu>
> > wrote:
> >>
> >> At Fri, 01 Mar 2013 09:05:21 +0100,
> >> Marijn wrote:
> >> > On 27-02-13 21:51, Neil Toronto wrote:
> >> >
> >> > > (An example that came up in the implementation of matrix norms: the
> >> > > type of (sqrt (/ 1 x)) isn't Nonnegative-Real if x :
> >> > > Nonnegative-Real, but Complex. Consider x = -0.0. Without TR's
> >> > > complaints, `matrix-norm' would have contained a time bomb.)
> >> >
> >> > Should -0.0 really be a Nonnegative-Real?
> >>
> >> That's by design.
> >>
> >> Including both floating-point zeroes in both non-negative and
> >> non-positive types is necessary to make occurrence typing useful for
> >> comparisons between floating-point numbers and zero (see PR12706 for
> >> more details). It also simplifies parts of the numeric base environment
> >> significantly.
> >>
> >> Vincent
> >>
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