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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 16:31:52 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1.50 (gnu/linux)

Andy Wingo <address@hidden> writes:

> On Wed 20 Jun 2012 15:41, Noah Lavine <address@hidden> writes:
>
>> I believe David's claim is that Guile should guarantee that a variable
>> is eq? to itself, even though the standard doesn't.
>
> We could guarantee this, but it would prevent a number of interesting
> and permissible optimizations, for questionable semantic value. 

Name one.

> You should not consider variables as having identity, only values.
> Numbers do not have identity, so Guile can do with them as it pleases.

Let's throw an error whenever using eq? on a number or running memq on a
list containing a number.

That would be interesting and apparently permissible behavior.  I have
my doubts that users will be impressed favorably.

-- 
David Kastrup



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