From: David Kastrup <dak@gnu.org>
To: 41354@debbugs.gnu.org
Subject: bug#41354: equal? has no sensible code path for symbols
Date: Sun, 17 May 2020 12:49:50 +0200 [thread overview]
Message-ID: <87v9kuzvht.fsf@fencepost.gnu.org> (raw)
In Scheme, symbols can be compared using eq? for equality. However,
since they have garbage-collected content attached, they do not meet the
predicate SCM_IMP in the short-circuit evaluation at the start of equal?
This means that unequal symbols compared using equal? fall through a
whole bunch of tests and end up in a general structural comparison
comparing their underlying string names.
This completely sabotages the semantics symbols are intended for.
Behavior for eqv? is similar but the fall-through at least is not as
expensive as it is for equal? .
--
David Kastrup
next reply other threads:[~2020-05-17 10:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-17 10:49 David Kastrup [this message]
2020-05-27 20:39 ` bug#41354: equal? has no sensible code path for symbols Ludovic Courtès
2020-05-27 20:49 ` David Kastrup
2020-05-28 16:06 ` Ludovic Courtès
2020-05-28 16:50 ` David Kastrup
2020-05-29 8:05 ` Ludovic Courtès
2021-01-19 21:53 ` David Kastrup
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