From: Eli Zaretskii <eliz@gnu.org>
To: Alex Gramiak <agrambot@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: [RFC] Some new vector procedures (vector-{memq, apply, to-string, ...})
Date: Sat, 20 Apr 2019 22:11:10 +0300 [thread overview]
Message-ID: <83tvesa3w1.fsf@gnu.org> (raw)
In-Reply-To: <87bm107d7q.fsf@gmail.com> (message from Alex Gramiak on Sat, 20 Apr 2019 12:18:01 -0600)
> From: Alex Gramiak <agrambot@gmail.com>
> Cc: emacs-devel@gnu.org
> Date: Sat, 20 Apr 2019 12:18:01 -0600
>
> Ideally. Though in the case of vector-partition the size of the 2
> partition vectors is not known in advance, so a Lisp implementation
> would have to create two extra Lisp vectors as opposed to using
> SAFE_ALLOCA. That is, unless Elisp grows a growable/resizeable vector
> type (which is something I was thinking about -- would that be denied?).
What would be the advantage of that vs lists?
> >> > As for speed, did you have any application where the speed of the Lisp
> Well, it's a stupid itch, but sometimes I see the (memq elt <list
> of constants>) and think that using a vector would be faster/better,
> mainly since memq has to check for cycles.
You mean 'member', right? I don't think 'memq' checks for cycles.
> More generally, there's currently no way to check existence in a
> vector nearly as fast as one can check existence in a list, which is
> unusual in programming languages.
Vectors are used quite rarely in Emacs Lisp, IME. I think we should
all keep in mind that Emacs Lisp is not a general-purpose language, it
is a language for implementing and extending Emacs.
> I don't believe that the vector-memq/member procedures would pose a
> maintenance burden like some of the others (vector-apply in particular)
> would.
Every additional primitive means a burden. More importantly, we
should IMO be consistent in how we design and implement families of
functions, which is why I still think we should extend seq.el
(possibly some of that with internal C primitives, if needed), instead
of starting a new family.
next prev parent reply other threads:[~2019-04-20 19:11 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-19 20:49 [RFC] Some new vector procedures (vector-{memq, apply, to-string, ...}) Alex Gramiak
2019-04-20 7:04 ` Eli Zaretskii
2019-04-20 16:50 ` Alex Gramiak
2019-04-20 17:16 ` Eli Zaretskii
2019-04-20 18:18 ` Alex Gramiak
2019-04-20 19:11 ` Eli Zaretskii [this message]
2019-04-20 19:54 ` Alan Mackenzie
2019-04-20 20:09 ` Óscar Fuentes
2019-04-20 22:54 ` Paul Eggert
2019-04-21 3:01 ` Using SMALL_LIST_LEN_MAX for memq and list_length (was: [RFC] Some new vector procedures (vector-{memq, apply, to-string, ...})) Alex Gramiak
2019-04-21 1:52 ` [RFC] Some new vector procedures (vector-{memq, apply, to-string, ...}) Alex Gramiak
2019-04-21 5:50 ` Eli Zaretskii
2019-04-21 4:05 ` Stefan Monnier
2019-04-21 20:34 ` Alex Gramiak
2019-04-21 21:01 ` Stefan Monnier
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