From: <tomas@tuxteam.de>
To: Atticus <atticus0@posteo.org>
Cc: 21855@debbugs.gnu.org
Subject: bug#21855: eq?
Date: Sun, 8 Nov 2015 11:23:23 +0100 [thread overview]
Message-ID: <20151108102323.GA5299@tuxteam.de> (raw)
In-Reply-To: <87r3k2ezjr.fsf@posteo.org>
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On Sat, Nov 07, 2015 at 01:58:48PM +0100, Atticus wrote:
> So I wanted to try out gnu guix and thus make myself more familiar with
> guile first. While running some tests I encountered a problem/bug with eq?:
>
> $ guile -v
> guile (GNU Guile) 2.1.1
>
> $ guile
> scheme@(guile-user)>
> (define (multirember a lat)
> (cond
> ((null? lat) '())
> ((eq? (car lat) a) (multirember a (cdr lat)))
> (else (cons (car lat) (multirember a (cdr lat))))))
>
> scheme@(guile-user)> (multirember '(a b) '(x y (a b) z (a b)))
> $1 = (x y z)
>
> So why does guile return (x y z)? I expected (x y (a b) z (a b)). I know
> eq? should only be used with symbols (and thus this example is more
> theoretical) but nevertheless the return value is not right, since (eq?
> '(a b) '(a b)) returns #f (Btw same in guile 2.0.11).
Hm. As far as I know (eq? '(a b) '(a b)) is not *guaranteed* to evaluate
to #f. The implementation might be free to re-use things it "knows" to be
constant (I might be wrong, though).
Regards
- -- t
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next prev parent reply other threads:[~2015-11-08 10:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-07 12:58 bug#21855: eq? Atticus
2015-11-08 10:23 ` tomas [this message]
2015-11-08 13:30 ` Atticus
2015-11-08 13:38 ` tomas
2015-11-09 7:57 ` Atticus
2016-06-24 15:31 ` Andy Wingo
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