From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg via Users list for the GNU Emacs text editor Newsgroups: gmane.emacs.help Subject: Re: Appending lists Date: Tue, 15 Jun 2021 10:27:48 +0200 Message-ID: <87y2bby1kr.fsf@zoho.eu> References: <4tl1yvylvg1fxx5eefjs9mnk.1623688568572@email.android.com> <87o8c8l32h.fsf@posteo.net> <87zgvs2bup.fsf@zoho.eu> Reply-To: Emanuel Berg Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="17609"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:3QvMKEpoKn5q09w5keN9ZHaOVOU= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Tue Jun 15 10:28:42 2021 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lt4R7-0004Oc-PT for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 15 Jun 2021 10:28:41 +0200 Original-Received: from localhost ([::1]:60774 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lt4R6-0003jA-SC for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 15 Jun 2021 04:28:40 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:42816) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lt4QS-0003hB-42 for help-gnu-emacs@gnu.org; Tue, 15 Jun 2021 04:28:00 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]:46828) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lt4QP-0003YF-Dg for help-gnu-emacs@gnu.org; Tue, 15 Jun 2021 04:27:59 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1lt4QN-0003P4-BJ for help-gnu-emacs@gnu.org; Tue, 15 Jun 2021 10:27:55 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:130864 Archived-At: > Also check out `nconc' > > (nconc '(1 2 3) '(4 5) '(6)) ; (1 2 3 4 5 6) - if this works for you, use it > (nconc '(1 2 3) '(4 5) 6 ) ; (1 2 3 4 5 . 6) - see, last "list" isn't a list! > > There was a trick with nconc, you could reverse a list in > constant time, right? I think that was it but that's all > I remember. Probably that wasn't `nconc' but `nreverse', I think! (nreverse '(flip six three hole)) ; (hole three six flip) Yeah, and it didn't take very long either... Here it says Don't use nreverse on quoted list literals; it is undefined behavior and may behave in surprising ways, since it is de facto self-modifying code. [1] Hm ... quoted list literals? Is this better? (nreverse (list 'flip 'six 'three 'hole)) ; (hole three six flip) Whats the difference and how does self-modifying code come in? I did that once but don't remember how it worked. Is that a function that modifies its own definition when executed? Funky ... but does that happen here? Where? But as for reversing the list it seems to "de facto" work anyway :) [1] https://stackoverflow.com/a/34423234 -- underground experts united https://dataswamp.org/~incal