[r6rs-discuss] div, mod, div0, mod0

[John Cowan]

On Fri, Aug 27, 2010 at 11:47 AM, Andy Wingo <wingo at pobox.com> wrote:

> What has the experience with div and mod been? The arguments in section
> 11.6.6 of the rationale sound convincing, but it is a change from Scheme
> going back to at least R2R6, and I would like to hear how people have
> found div and mod to be, in practice.

I can't speak to that directly, but I would like to advertise Taylor
Campbell's write-up of the issues, which I think is excellent. The
problems with the R5RS names is that they are basically Maclisp names
that escaped the Great Renaming, perhaps because they were
inadequately analyzed at the time.  I haven't tested it, but I bet
there are lots of implementations that get the edge cases wrong.  R6RS
replaced both names and functions, but the results are still highly
irregular, and people don't have a clear idea of which one does what.

The write-up:  http://mumble.net/~campbell/tmp/division.txt