[m-rev.] for discussion: undefined behaviours in int.m

[Zoltan Somogyi]

On Fri, 21 Oct 2016 02:56:26 +1100 (AEDT), Julien Fischer <jfischer at opturion.com> wrote:
> Is there any reason not to require 2's complement integer representation for
> Mercury ints?

No.

While some early computers used other representations for integers
(sign+magnitude, or one's complement), those have all died out.

> (On a related issue: does anyone have an objection to use requiring that
> Mercury floats be IEEE 754 single or double precision values?)

I have no objection to requiring IEEE 754. There is still an instruction set
in use today that uses pre-754 float representations, IBM's old format
from the System 360, but it doesn't matter to us, since I believe the IBM
mainframes that implement those old non-754 formats implement
the 754 formats as well.

I do object to requiring Mercury floats to be either singles or doubles,
because there are actually good reasons for number-crunching programs
to use quad precision. We don't support this currently, but there is no
reason why should close off the possibility for the future.

Zoltan.