From: "Mattias Engdegård" <mattiase@acm.org>
To: Robert Pluim <rpluim@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: master d62766305a: Add `take` and `ntake` (bug#56521)
Date: Mon, 18 Jul 2022 12:59:51 +0200 [thread overview]
Message-ID: <2BF27629-33F1-42CF-95A5-3C2EBD4A0DD1@acm.org> (raw)
In-Reply-To: <87r12ierhi.fsf@gmail.com>
18 juli 2022 kl. 10.48 skrev Robert Pluim <rpluim@gmail.com>:
> Does this need the usual blurb to do
>
> (setq list-var (ntake 3 list-var))
>
> to ensure `list-var' is updated?
Sort of; I added some text to that effect. Using the return value is only needed if N can be nonpositive.
> I think this would be clearer as
>
> "If N is >= the length of LIST, return LIST (or a copy)."
>
> since weʼre talking about the effect of various values of N.
Right, it's now been changed to something like that. Thank you!
Now `seq-take` uses `take`, and so does `seq-subseq`. This made both faster, but the latter was boosted immensely by not formatting an error string up-front.
`seq-subseq` would be even faster if simply written as
(take (- end start) (nthcdr start sequence))
but the interface requirements force a much more cumbersome implementation. (And does it really need `copy-sequence`? The docs are unclear.)
I suppose that `seq-subseq` should use `cl-defmethod` for dispatching on type but I didn't change that part.
next prev parent reply other threads:[~2022-07-18 10:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <165807284522.13427.2673143161208860104@vcs2.savannah.gnu.org>
[not found] ` <20220717154726.F2455C00095@vcs2.savannah.gnu.org>
2022-07-18 8:48 ` master d62766305a: Add `take` and `ntake` (bug#56521) Robert Pluim
2022-07-18 10:59 ` Mattias Engdegård [this message]
2022-07-18 11:55 ` Robert Pluim
2022-07-18 16:34 ` Michael Heerdegen
2022-07-18 17:21 ` Sam Steingold
2022-07-18 18:56 ` Philip Kaludercic
2022-07-18 22:57 ` Sam Steingold
2022-07-19 10:20 ` Mattias Engdegård
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