Re: [Scheme-reports] Formal Comment: R7RS 'eqv?' cannot be used for reliable memoization

Alex Shinn <alexshinn@x> writes:

> Thank you for the well reasoned formal comment. Note
>
> the formal comment period ended June 30,

For the record, lest anyone believe that I waited too long
to bring this up, I first raised this issue here on May 7:

http://lists.scheme-reports.org/pipermail/scheme-reports/2012-May/002153.html

> and we've
> published a draft which many people are now reviewing and
> will be used for the ratification vote. I will discuss with the WG,
> but it is unlikely we would consider such a change at this late time.

What is the purpose of allowing people to review a draft if you are
unwilling to fix serious flaws such as this?

If a serious flaw turned up even at this late stage

we would address it.

I do not consider this a serious flaw. I dislike it and

voted against it, but it's a reasonable specification of

eqv?.

First, the implementation strategy you suggest is only

hypothetical. Although I agree MPFR is a worthwhile

target, no such implementations exist yet. Actual

working code speaks much louder than ideas.

Second, the only potential difference between the

current draft and your proposal is with -0.0, which does

not mathematically exist. One can argue that the MPRF

implementation of -0.0 is an implementation of the IEEE

754 value, and so you can treat this the same without

even a disclaimer.

Alex