GNU bug report logs - #42147
28.0.50; pure vs side-effect-free, missing optimizations?

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Package: emacs;

Reported by: Andrea Corallo <andrea_corallo <at> yahoo.it>

Date: Tue, 30 Jun 2020 22:28:02 UTC

Severity: normal

Found in version 28.0.50

Done: Mattias Engdegård <mattiase <at> acm.org>

Bug is archived. No further changes may be made.

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Message #71 received at 42147 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattiase <at> acm.org>
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, Stefan Monnier <monnier <at> iro.umontreal.ca>,
 Andrea Corallo <andrea_corallo <at> yahoo.it>, 42147 <at> debbugs.gnu.org
Subject: Re: bug#42147: 28.0.50; pure vs side-effect-free, missing
 optimizations?
Date: Fri, 3 Jul 2020 11:25:30 +0200

2 juli 2020 kl. 21.09 skrev Philipp Stephani <p.stephani2 <at> gmail.com>:

> I don't think most of those are pure, as they have to "look into" an
> object. For example, the result of "equal" does not only depend on the
> argument objects, but also the objects they refer to.

Unless I'm mistaken, they are pure enough for the purpose of constant folding, where the arguments are already known (constant) at compile-time; do come with a counter-example if you disagree.

Were you thinking about other uses of pure functions? Perhaps our notion of purity is underspecified.
This bug report was last modified 4 years and 281 days ago.

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