GNU bug report logs - #41354
equal? has no sensible code path for symbols

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: David Kastrup <dak <at> gnu.org>
To: bug-guile <at> gnu.org
Subject: equal? has no sensible code path for symbols
Date: Sun, 17 May 2020 12:49:50 +0200

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

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