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Re: Bug in documentation for eq? ?


From: David Kastrup
Subject: Re: Bug in documentation for eq? ?
Date: Wed, 20 Jun 2012 17:25:03 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1.50 (gnu/linux)

Pierpaolo Bernardi <address@hidden> writes:

> On Wed, Jun 20, 2012 at 4:27 PM, David Kastrup <address@hidden> wrote:
>> Andy Wingo <address@hidden> writes:
>>
>> If the Scheme standard states that
>>
>> (and (pair? x) (not (eq? (car x) (car x))))
>>
>> can return #t in a conforming implementation, that means that the
>> standard failed to do its job for weeding out implementations with
>> unusable behavior.
>
> The standard did its job by defining eqv?
>
> Do a (define eq? eqv?) at the start of your programs and you have what
> you are asking for.

Except efficiency.  It appears you are confused about what I am asking
for.

I am perfectly fine with the possibility (eq? 0 0) => #f
I am not fine with the possibility (eq? (car x) (car x)) => #f

But it is clear that there is no interest in providing sane invariants
for Guile programmers, so we can just quit this absurdity.

-- 
David Kastrup




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