From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Replace element in list Date: Mon, 02 Sep 2019 10:57:06 -0400 Message-ID: References: <6a632b18-bbd6-7096-229d-6c890b6bdb6f@easy-emacs.de> <20190902134342.GG1466@tuxteam.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="267866"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon Sep 02 16:57:44 2019 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1i4nm0-0017TK-S3 for geh-help-gnu-emacs@m.gmane.org; Mon, 02 Sep 2019 16:57:40 +0200 Original-Received: from localhost ([::1]:37230 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i4nlz-000205-Q3 for geh-help-gnu-emacs@m.gmane.org; Mon, 02 Sep 2019 10:57:39 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:35074) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i4nlm-0001yq-Eu for help-gnu-emacs@gnu.org; Mon, 02 Sep 2019 10:57:27 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i4nll-0000dJ-Gs for help-gnu-emacs@gnu.org; Mon, 02 Sep 2019 10:57:26 -0400 Original-Received: from 195-159-176-226.customer.powertech.no ([195.159.176.226]:36730 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i4nll-0000Wx-AA for help-gnu-emacs@gnu.org; Mon, 02 Sep 2019 10:57:25 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1i4nlf-00179k-95 for help-gnu-emacs@gnu.org; Mon, 02 Sep 2019 16:57:19 +0200 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:4puXMqvBPDm441mZZrUJ+2dFCCU= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 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.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.org gmane.emacs.help:121426 Archived-At: >>> is that if you need to do that, there's a problem upstream. ^^^ probably >>> E.g. could you use a struct instead of a list? >> Thanks for putting my mumbling into civilised words :-) > Hmm, what means struct here? Something defined with `cl-defstruct`. But in your example, you want to use a vector instead. > But that was easier to read: I must admit I do not see which aspect of the change you think makes it more readable, nor why using a list is related to it. > (defun state_A (elist pos) >   (if (eq 1 (nth pos elist)) >       (progn >     (setf (nth pos elist) 0) >     (state_B elist (1- pos))) >     (message "Fertig %s" elist))) > > (defun statemachine () >   (interactive) >   (let ((elist (list 0 0 0 0 1 1 0 0 0)) >     (pos 5)) >     (state_A elist pos))) Replace `nth` with `aref` (and swap the args accordingly) and replace (list ...) with (vector ...) and you've got a solution using vectors instead of lists. BTW, the traditional name for your "elist" is "tape" ;-) Stefan