<div dir="ltr">Yes, you're right. Sorry for that confusion. I don't have that confusion with positive? and +0.0, after all!<div><br>Robby</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Mar 1, 2013 at 10:50 AM, Eric Dobson <span dir="ltr"><<a href="mailto:eric.n.dobson@gmail.com" target="_blank">eric.n.dobson@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Why is Nonnegative-Real not suggestive of the right thing? To me that<br>
means (and/c real? (not/c (lambda (x) (< x 0)))) which is exactly what<br>
it is.<br>
<br>
I think the confusing part is that -0.0 has a minus sign in front<br>
which means that you think it is negative, but this isn't true.<br>
<div class="HOEnZb"><div class="h5"><br>
On Fri, Mar 1, 2013 at 8:31 AM, Robby Findler<br>
<<a href="mailto:robby@eecs.northwestern.edu">robby@eecs.northwestern.edu</a>> wrote:<br>
> Is there perhaps a more suggestive name? (Not that I'm coming up with<br>
> one...)<br>
><br>
> Robby<br>
><br>
><br>
> On Fri, Mar 1, 2013 at 10:22 AM, Vincent St-Amour <<a href="mailto:stamourv@ccs.neu.edu">stamourv@ccs.neu.edu</a>><br>
> wrote:<br>
>><br>
>> At Fri, 01 Mar 2013 09:05:21 +0100,<br>
>> Marijn wrote:<br>
>> > On 27-02-13 21:51, Neil Toronto wrote:<br>
>> ><br>
>> > > (An example that came up in the implementation of matrix norms: the<br>
>> > > type of (sqrt (/ 1 x)) isn't Nonnegative-Real if x :<br>
>> > > Nonnegative-Real, but Complex. Consider x = -0.0. Without TR's<br>
>> > > complaints, `matrix-norm' would have contained a time bomb.)<br>
>> ><br>
>> > Should -0.0 really be a Nonnegative-Real?<br>
>><br>
>> That's by design.<br>
>><br>
>> Including both floating-point zeroes in both non-negative and<br>
>> non-positive types is necessary to make occurrence typing useful for<br>
>> comparisons between floating-point numbers and zero (see PR12706 for<br>
>> more details). It also simplifies parts of the numeric base environment<br>
>> significantly.<br>
>><br>
>> Vincent<br>
>><br>
>> _________________________<br>
>> Racket Developers list:<br>
>> <a href="http://lists.racket-lang.org/dev" target="_blank">http://lists.racket-lang.org/dev</a><br>
><br>
><br>
><br>
> _________________________<br>
> Racket Developers list:<br>
> <a href="http://lists.racket-lang.org/dev" target="_blank">http://lists.racket-lang.org/dev</a><br>
><br>
_________________________<br>
Racket Developers list:<br>
<a href="http://lists.racket-lang.org/dev" target="_blank">http://lists.racket-lang.org/dev</a><br>
</div></div></blockquote></div><br></div>