From: Dmitry Gutov <dmitry@gutov.dev>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: Yuri Khan <yuri.v.khan@gmail.com>, Eli Zaretskii <eliz@gnu.org>,
John Wiegley <jwiegley@gmail.com>,
emacs-devel@gnu.org
Subject: Re: master 4b79c80c999 1/2: New function 'sort-on'
Date: Sat, 2 Mar 2024 01:37:01 +0200 [thread overview]
Message-ID: <8b31204f-4e8c-4c56-bbc7-73c9bfabb651@gutov.dev> (raw)
In-Reply-To: <87zfvldokn.fsf@web.de>
On 28/02/2024 09:40, Michael Heerdegen wrote:
> Dmitry Gutov <dmitry@gutov.dev> writes:
>
>> The other alternative (suggested by Daniel) is to add a yet another
>> optional argument - whether to do the schwartz transform - so it would
>> be on the caller to determine whether the accessor is costly enough.
>
> This would be my preferred solution, too
>
>> This is not my first choice, but I'd still prefer it over having two
>> different but very similar functions. sort-on is slower than it has to
>> be, too.
>
> It could be improved? How?
Well, 'mapcar' in it allocates a new sequence of length N. The Schwartz
transform creates about as many new cons cells too. If the function is
made destructive, 'mapcar' becomes unnecessary as the original sequence
could be reused - and that is measurably faster, too (when the cost
function is simple enough).
And if it's made destructive, it becomes even closer to the current
'sort'. That would mean less justification to keep them as separate
functions.
> BTW, I wonder how this addition fits into my original suggestion about
> sort predicate construction.
Sorry, I either can't find your respective message in this thread, or
don't understand the suggestion.
> I guess we would want to allow to choose
> between using schwartz or not (at each level) in the specification -
I don't know if we really want to (every such knob is a step toward more
complex api, and higher odds of user choosing the parameters poorly),
but we could indeed try something like that.
> which would mean that my approach would build a sort function, not a
> sort predicate. Which also might allow to build more efficient code.
If you mean that your proposed constructed sort function would
incorporate the lookup logic (currently supplied with ACCESSOR), then it
would incur the same cost that the Schwartz transform is amortizing,
wouldn't it? Perhaps some code would help.
Also, if the sort function will be in Lisp (even byte-compiled one),
then it will likely have higher overhead than the simple '< or 'string<,
for example. And while the cost of the transform is O(N), the comparison
function is called O(N*logN) on average.
next prev parent reply other threads:[~2024-03-01 23:37 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <170688047526.14693.2994051491358257471@vcs2.savannah.gnu.org>
[not found] ` <20240202132756.4272CC0EFE7@vcs2.savannah.gnu.org>
2024-02-02 15:00 ` master 4b79c80c999 1/2: New function 'sort-on' Daniel Mendler via Emacs development discussions.
2024-02-02 15:04 ` Eli Zaretskii
2024-02-02 15:26 ` Daniel Mendler via Emacs development discussions.
2024-02-02 15:47 ` Eli Zaretskii
2024-02-02 16:05 ` Daniel Mendler via Emacs development discussions.
2024-02-05 12:14 ` Michael Heerdegen
2024-02-02 15:55 ` Dmitry Gutov
2024-02-02 15:30 ` Michael Heerdegen via Emacs development discussions.
2024-02-02 15:35 ` Daniel Mendler via Emacs development discussions.
2024-02-02 16:08 ` Michael Heerdegen via Emacs development discussions.
2024-02-02 16:23 ` Daniel Mendler via Emacs development discussions.
2024-02-02 16:43 ` Michael Heerdegen via Emacs development discussions.
2024-02-02 15:50 ` Eli Zaretskii
2024-02-02 16:06 ` Eshel Yaron
2024-02-02 16:34 ` Eli Zaretskii
2024-02-02 16:46 ` Michael Heerdegen via Emacs development discussions.
2024-02-02 17:55 ` Emanuel Berg
2024-02-05 0:48 ` Dmitry Gutov
2024-02-05 5:30 ` Yuri Khan
2024-02-05 12:52 ` Eli Zaretskii
2024-02-05 13:25 ` Dmitry Gutov
2024-02-05 14:31 ` Eli Zaretskii
2024-02-05 14:47 ` Dmitry Gutov
2024-02-05 15:10 ` Eli Zaretskii
2024-02-05 15:29 ` Dmitry Gutov
2024-02-28 7:40 ` Michael Heerdegen
2024-03-01 23:37 ` Dmitry Gutov [this message]
2024-03-04 6:45 ` Michael Heerdegen
2024-03-04 16:43 ` Dmitry Gutov
2024-03-05 8:06 ` Michael Heerdegen
2024-03-05 10:21 ` Michael Heerdegen via Emacs development discussions.
2024-03-05 12:39 ` Eli Zaretskii
2024-03-06 3:20 ` Michael Heerdegen
2024-03-06 12:10 ` Eli Zaretskii
2024-03-06 18:34 ` Dmitry Gutov
2024-03-06 20:12 ` John Wiegley
2024-03-07 1:34 ` Dmitry Gutov
2024-03-05 12:44 ` Dmitry Gutov
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