[racket-dev] [racket] Question about round

Doesn't it already? The docs say

  `Integer' includes only integers that are exact numbers,
  corresponding to the predicate `exact-integer?'.

Even if the type were currently `Exact-Integer', it sounds like you
mean just renaming to `Integer'.

I think a change to the number hierarchy would mean changing functions
so that they produce different results on particular inputs than they
do now. That doesn't seem to be a part of Vincent's suggestion.

At Fri, 30 Sep 2011 14:02:50 -0400, Matthias Felleisen wrote:
> 
> Yes, there is. The type Integer would denote the 
> exact integers now. 
> 
> In general, I wanted to this email into a larger
> context. 
> 
> 
> 
> On Sep 30, 2011, at 2:01 PM, Matthew Flatt wrote:
> 
> > Vincent's proposal seemed to me to be just a renaming the current
> > functions. Is there an intended change to the numeric tower that I'm
> > missing?
> > 
> > At Fri, 30 Sep 2011 13:28:12 -0400, Matthias Felleisen wrote:
> >> 
> >> I sent this to Matthew privately but I think we need to be
> >> much more careful with 'interesting'. While you are right 
> >> about the 'wired into our code' part, I think the two of 
> >> you are wrong about the 'interesting' part. 
> >> 
> >> From a type perspective, the numeric tower comes with major
> >> flaws and it would be wonderful if a language that divorces
> >> itself from the old flawed Scheme world could make a clean
> >> cut and do better. 
> >> 
> >> But I am also the person who preaches 'the path from here to
> >> there' and agree that the 'wired' argument for the existing
> >> code base and outside consumers tells us that Racket isn't 
> >> the language that can fix these mistakes. 
> >> 
> >> 
> >> 
> >> 
> >> On Sep 30, 2011, at 12:32 PM, Robby Findler wrote:
> >> 
> >>> This is my opinion, too.
> >>> 
> >>> Robby
> >>> 
> >>> On Fri, Sep 30, 2011 at 11:20 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> >>>> I think this is a good change for the next language, but not for `#lang
> >>>> racket'.
> >>>> 
> >>>> As confusing as the current `integer?' may be, I think its definition
> >>>> is deeply wired into our code, tests, and documentation. I may guess
> >>>> wrong, but my best estimate of the hassle for this change is that it's
> >>>> too much trouble for too little payoff, and we could spend our energy
> >>>> on more interesting things.
> >>>> 
> >>>> At Fri, 30 Sep 2011 11:59:25 -0400, Vincent St-Amour wrote:
> >>>>> On a more general note, do we really need inexact integers?
> >>>>> 
> >>>>> The behavior of `integer?' is confusing, and I don't see especially
> >>>>> compelling reasons to keep it this way. The subject comes up every
> >>>>> couple of months on the mailing list, so we should do something about it.
> >>>>> 
> >>>>> Here's a proposal:
> >>>>> `integer?' becomes the same as `exact-integer?' (which is kept for
> >>>>> backwards compatibility).
> >>>>> `positive-integer?' and `nonnegative-integer?' are added as
> >>>>> equivalents to their `exact' counterparts.
> >>>>> `inexact-integer?' is added, to cover for the use case of checking is
> >>>>> an inexact number has been rounded.
> >>>>> 
> >>>>> I volunteer to implement this if we agree that this is the right
> >>>>> thing.
> >>>>> 
> >>>>> Vincent
> >>>>> 
> >>>>> 
> >>>>> 
> >>>>> At Fri, 30 Sep 2011 07:16:22 -0600,
> >>>>> Doug Williams wrote:
> >>>>>> 
> >>>>>> Another such annoyance is than (min 1 +inf.0) => 1.0 - because if any
> >>>>>> argument is inexact, the result is inexact. I don't think this makes 
> sense
> >>>>>> in the case of infinities. Infinities are very useful as initial values 
> >> for
> >>>>>> things that are being minimized or maximized, but there is always the 
> need
> >>>>>> for inexact->exact to protect against the (unexpected) coercion.
> >>>>>> 
> >>>>>> This is all from the original R5RS and continued in R6RS - but, we 
> aren't
> >>>>>> that language.
> >>>>>> 
> >>>>>> Could we get an exception to the coercions in the case of +/-inf.0? Or 
> an
> >>>>>> alternative min/max that don't do it?
> >>>>>> 
> >>>>>> On Fri, Sep 30, 2011 at 6:53 AM, Matthias Felleisen
> >>>>> <matthias at ccs.neu.edu>wrote:
> >>>>>> 
> >>>>>>> 
> >>>>>>> exact-round is preferred.
> >>>>>>> 
> >>>>>>> 
> >>>>>>> 
> >>>>>>> On Sep 30, 2011, at 8:51 AM, Eli Barzilay wrote:
> >>>>>>> 
> >>>>>>>> Yesterday, Ryan Culpepper wrote:
> >>>>>>>>> The pragmatic answer is you generally have to write
> >>>>>>>>> 
> >>>>>>>>>  (inexact->exact (round x))
> >>>>>>>>> 
> >>>>>>>>> which is annoying, but no one has yet bothered to add a standard
> >>>>>>>>> library function for this, as far as I know.
> >>>>>>>> 
> >>>>>>>> [From the annoyed side, especially since that thing tends to come in
> >>>>>>>> bunches which can make some quick code look much heavier than it is:]
> >>>>>>>> 
> >>>>>>>> Maybe it's time to add something for that?  `eround'?  (But even
> >>>>>>>> `exact-round' would be better than the above.)
> >>>>>>>> 
> >>>>>>>> --
> >>>>>>>>         ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
> >>>>>>>>                   http://barzilay.org/                   Maze is Life!
> >>>>>>>> _________________________________________________
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