bug#69709: `sort` interface improvement and universal ordering predicate

[Mattias Engdegård]

10 mars 2024 kl. 15.09 skrev Eli Zaretskii <eliz@gnu.org>:

> A nit: let's go with a name that doesn't have "new" as part of it.

Sorry, that was meant as a placeholder. I should have used a more obvious 
non-name.

> Do you intend to present an implementation that replaces sort-on as
> well?

Yes, `sort-on` would be completely subsumed by the new interface.

> And what about performance?

Existing code should see little or no change. Users of the new interface would 
probably see performance improvements. You should trust me on neither of these 
points until there is actual code.

However the performance of the universal predicate seems fine, and is 
definitely better than hand-writing a predicate in Lisp when applicable.