[Haskell-cafe] Re: Difference between div and /

[Daniel Fischer]

On Wednesday 02 June 2010 00:55:08, Maciej Piechotka wrote:
> On Tue, 2010-06-01 at 15:29 -0700, Evan Laforge wrote:
> > > [1] By co I mean Ruby, Python, Perl and others. There are no so many
> > > languages that do recognize the difference.
> >
> > % python -Q new
> > Python 2.4.6 (#1, Aug  3 2009, 17:05:16)
> > [GCC 4.0.1 (Apple Inc. build 5490)] on darwin
> > Type "help", "copyright", "credits" or "license" for more information.
> > 10 / 3
> > #-> 3.3333333333333335
> > 10 // 3
> > #-> 3
> >
> >
> > The python guys decided that int/int -> int was a mistake, but because
> > it's an incompatible change, the removal process has been long (hence
> > the -Q flag, or a from __future__ import).  In fact, I think they gave
> > up on making it the default before python 3.
> >
> > I appreciate that haskell has differentiated from the beginning.
>
> Well - i tried to write some package dealing with distributions etc.
>
> If you have something like that:
>
> instance ... => Distribution (Linear a) a where
>     rand (Linear f s) g =
>         let (gf, gt) = genRange g
>             (v, g') = next g
>         in (g', f + (fromIntegral v * s) / fromIntegral (gt - gf))
>
> (I haven't check it but IMHO it is right implementation)
>
> Now I have following options:
>
>  - Implement per Int/Int8/...
>  - Implement IntegerLinear and FractionalLinear separatly

- use realToFrac instead of fromIntegral
(using the logfloat package is probably not a bad idea then)

>
> Neither of choices are IMHO not ideal.

Methinks that is not what you wanted to say ;)

>
> Regards