Re: master 82cc1f4fda1: Revert use of seq-count in shr-count

[Philip Kaludercic]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Wed, 06 Sep 2023 14:34:35 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: philipk@posteo.net, emacs-devel@gnu.org, stefankangas@gmail.com
>> 
>> > From: Karthik Chikmagalur <karthikchikmagalur@gmail.com>
>> > Cc: emacs-devel@gnu.org, stefankangas@gmail.com
>> > Date: Tue, 05 Sep 2023 17:02:03 -0700
>> > 
>> > > I think we should start by measuring its actual performance as
>> > > compared to more "traditional" implementations.  Then we will have the
>> > > base line and data for making the decisions.
>> > 
>> > There are some benchmarks by Kisaragi Hiu comparing seq, cl-lib and dash
>> > on Emacs 28.1 here:
>> > 
>> > https://kisaragi-hiu.com/performance-cl-lib-dash-seq/
>> > 
>> > seq appears to be much slower than cl-lib.
>> 
>> Then I agree that we should convert to seq with caution, only where we
>> are sure that the slowdown won't matter much, and we should always
>> time the old vs the new code before making the decision.
>
> Of course, speeding up seq would be even better.

There seems to be ways for common lisp to statically dispatch the right
implementations, but I don't understand enough of it to judge if
something like this would be possible for cl-generic:
https://github.com/marcoheisig/fast-generic-functions