From: "Mattias Engdegård" <mattiase@acm.org>
To: sds@gnu.org
Cc: emacs-devel@gnu.org
Subject: Re: lexicographic list comparison
Date: Sat, 10 Sep 2022 11:07:49 +0200 [thread overview]
Message-ID: <E79429C1-EBAA-4601-A818-1BDF6745B7B1@acm.org> (raw)
In-Reply-To: <lz4jxg8i19.fsf@3c22fb11fdab.ant.amazon.com>
9 sep. 2022 kl. 21.27 skrev Sam Steingold <sds@gnu.org>:
> What do you do when sorting a list of lists of numbers?
Sigh deeply and write ad-hoc code for the nth time.
> Or maybe sorting lists of lists is just such a rare op that no one has
> ever encountered it before me?
It would be useful to have a total ordering on Lisp values: for heterogeneous ordered collections, for simplifying multi-key sorting, for normalising unordered collections, etc.
The devil is in the details: are strings compared with our without properties? Do we observe the wonky IEEE rules for ordering floats? Is there a particularly useful ordering between elements of different types? Do we need to worry about circularity? How do we compare hash tables? And so on.
Consistency with `equal` would be desirable (up to hash table identity, perhaps).
next prev parent reply other threads:[~2022-09-10 9:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-09 19:27 lexicographic list comparison Sam Steingold
2022-09-10 9:07 ` Mattias Engdegård [this message]
2022-09-10 9:22 ` Emanuel Berg
2022-09-10 9:26 ` tomas
2022-09-12 14:45 ` Sam Steingold
2022-09-12 17:53 ` mattiase
2022-09-12 18:31 ` Stefan Monnier
2022-09-12 18:41 ` Sam Steingold
2022-09-12 19:32 ` Stefan Monnier
2022-09-12 18:35 ` Sam Steingold
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