From: Heime <heimeborgia@protonmail.com>
To: Emanuel Berg <incal@dataswamp.org>
Cc: help-gnu-emacs@gnu.org
Subject: Re: Easy to add with push but not to the end of a list
Date: Mon, 28 Nov 2022 22:01:24 +0000 [thread overview]
Message-ID: <sIYWZG2CBWRu6rG6C9-libd9CHuNuvzkkk7-v-BO-GGhK-bqDPsRitUkjXU6b3MmThCRR5B2Ud3tuNLmgfkb56meosTPKVF0wjICDt2mlbA=@protonmail.com> (raw)
In-Reply-To: <878rju96i5.fsf@dataswamp.org>
------- Original Message -------
On Monday, November 28th, 2022 at 8:19 PM, Emanuel Berg <incal@dataswamp.org> wrote:
> Stefan Monnier via Users list for the GNU Emacs text editor wrote:
>
> > > Although it is easy to add to a list using push, it
> > > currently looks hideous to be able to add to the end of
> > > a list.
> >
> > That's because adding to the end of a Lisp list is
> > a bad idea.
The bad idea comment disregards necessity. Suppose I am accumulating
indicators that are done at increasing value of time and want to introduce
them into another list in the order they were encountered. What should one
handle these things?
> Let's make it as good as possible first ...
>
> Why is the below O(N), because of `last'?
>
> (defun push-last (elem lst)
> (let ((elem-lst (list elem)))
> (if lst
> (setcdr (last lst) elem-lst)
> (setq lst elem-lst) )
> lst) )
>
> ;; (setq nil-lst nil)
> ;;
> ;; (push-last 1 nil-lst) ; (1)
> ;;
> ;; (setq lst '(1 2 3 4))
> ;;
> ;; (push-last 5 lst) ; (1 2 3 4 5)
> ;;
> ;; lst ; (1 2 3 4 5)
>
> --
> underground experts united
> https://dataswamp.org/~incal
next prev parent reply other threads:[~2022-11-28 22:01 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-28 2:26 Easy to add with push but not to the end of a list Heime
2022-11-28 2:43 ` [External] : " Drew Adams
2022-11-28 3:45 ` Heime
2022-11-28 6:11 ` Drew Adams
2022-11-28 20:00 ` Emanuel Berg
2022-11-28 5:18 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-11-28 20:19 ` Emanuel Berg
2022-11-28 21:56 ` [External] : " Drew Adams
2022-11-28 22:45 ` Emanuel Berg
2022-11-28 22:01 ` Heime [this message]
2022-11-28 22:24 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-11-28 22:58 ` Emanuel Berg
2022-11-30 14:10 ` tomas
2022-11-30 16:12 ` Emanuel Berg
2022-11-28 22:46 ` Emanuel Berg
2022-11-28 22:50 ` Emanuel Berg
2022-11-29 5:23 ` tomas
2022-11-29 5:32 ` Emanuel Berg
2022-11-29 7:56 ` Heime
2022-11-29 8:33 ` Marcin Borkowski
2022-11-29 10:00 ` Emanuel Berg
2022-11-29 10:05 ` Emanuel Berg
2022-11-29 10:15 ` Heime
2022-11-29 8:38 ` tomas
2022-11-29 9:54 ` Emanuel Berg
2022-11-29 8:17 ` Marcin Borkowski
2022-11-29 8:44 ` tomas
2022-11-29 12:08 ` Dr Rainer Woitok
2022-11-29 19:54 ` Of cars and mice [was: Easy to add with push but not to the end of a list] tomas
2022-11-30 1:17 ` Emanuel Berg
2022-11-30 1:13 ` Easy to add with push but not to the end of a list Emanuel Berg
2022-11-28 19:59 ` Emanuel Berg
2022-11-28 21:56 ` [External] : " Drew Adams
2022-11-28 22:18 ` Heime
2022-11-28 22:41 ` Drew Adams
2022-11-29 11:17 ` Dr Rainer Woitok
2022-11-30 17:10 ` Michael Heerdegen
2022-11-30 18:17 ` [External] : " Drew Adams
2022-11-30 19:30 ` Emanuel Berg
2022-12-01 15:11 ` Michael Heerdegen
2022-12-01 17:25 ` Emanuel Berg
2022-12-03 21:29 ` Michael Heerdegen
2022-12-05 23:35 ` Emanuel Berg
2022-12-06 1:36 ` Michael Heerdegen
2022-12-06 1:43 ` Emanuel Berg
2022-12-06 2:17 ` Michael Heerdegen
2022-12-06 2:40 ` Emanuel Berg
2022-12-06 13:56 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-12-06 14:45 ` Michael Heerdegen
2022-12-06 2:52 ` Emanuel Berg
2022-12-06 17:22 ` Michael Heerdegen
2022-12-06 22:30 ` Emanuel Berg
2022-12-08 23:15 ` Michael Heerdegen
2022-12-28 23:52 ` Emanuel Berg
2022-12-31 16:57 ` Michael Heerdegen
2022-12-31 22:09 ` Emanuel Berg
2023-01-01 12:16 ` Michael Heerdegen
2023-01-08 4:40 ` Emanuel Berg
2023-01-09 6:32 ` Emanuel Berg
2023-01-14 12:05 ` Michael Heerdegen
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