[racket-dev] [racket] Question about round

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!
> > > _________________________________________________
> > >  For list-related administrative tasks:
> > >  http://lists.racket-lang.org/listinfo/users
> >
> > _________________________________________________
> >  For list-related administrative tasks:
> >  http://lists.racket-lang.org/listinfo/users
> >