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

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From: Mattias Engdegård <mattiase <at> acm.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Philipp Stephani <p.stephani2 <at> gmail.com>, Paul Eggert <eggert <at> cs.ucla.edu>, Andrea Corallo <andrea_corallo <at> yahoo.it>, 42147 <at> debbugs.gnu.org
Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations?
Date: Mon, 3 Aug 2020 17:07:35 +0200

29 juli 2020 kl. 22.39 skrev Stefan Monnier <monnier <at> iro.umontreal.ca>:
> 
>> Regarding package-get-version: perhaps we should drop the 'pure' property
>> and just let callers wrap it in eval-when-compile?
> 
> I'd rather not: the benefit is too subtle, I'd expect most users won't
> know/bother to use `eval-when-compile` around it even though I'd expect
> a vast majority of the uses can benefit from compile-time evaluation.
> In contrast the cases where the impurity will get in the way
> should be rare.  Feel free to add a `save-match-data` if you think it's
> worth the trouble (but please include a comment explaining it's only
> there in order to satisfy the `pure` annotation).

Thank you, I'll let you make the decision since you introduced the function. Another possibility would be to turn it into a macro again (or more likely a macro that calls a function at compile-time), or use define-inline.

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