From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: Re: [External] : How to create a higher order function? Date: Tue, 05 Oct 2021 09:25:52 +0200 Message-ID: <875yuc7x1b.fsf@mbork.pl> References: <87k0jawotx.fsf@mbork.pl> <87czoyfipj.fsf@mbork.pl> <87k0j6gvpd.fsf@zoho.eu> <871r5dhp9q.fsf@zoho.eu> <87tui99n63.fsf@mbork.pl> <87mto0usgs.fsf@zoho.eu> <87h7e69vng.fsf@mbork.pl> <87fstpo4sv.fsf@zoho.eu> <87y27g8vwb.fsf@mbork.pl> <87czosqa3q.fsf@zoho.eu> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="5664"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 28.0.50 Cc: help-gnu-emacs@gnu.org To: Emanuel Berg Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Tue Oct 05 09:27:04 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 1mXequ-0001FW-80 for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 05 Oct 2021 09:27:04 +0200 Original-Received: from localhost ([::1]:56784 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mXeqt-0006tT-8l for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 05 Oct 2021 03:27:03 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:37328) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mXeq8-0006qt-NV for help-gnu-emacs@gnu.org; Tue, 05 Oct 2021 03:26:16 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:41084) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mXeq0-0004DE-Jm for help-gnu-emacs@gnu.org; Tue, 05 Oct 2021 03:26:16 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id 3C8E4E6AC9; Tue, 5 Oct 2021 09:25:58 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id AStHW31zzxMZ; Tue, 5 Oct 2021 09:25:53 +0200 (CEST) Original-Received: from localhost (178235147119.dynamic-3-poz-k-0-1-0.vectranet.pl [178.235.147.119]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 201CDE681D; Tue, 5 Oct 2021 09:25:53 +0200 (CEST) In-reply-to: <87czosqa3q.fsf@zoho.eu> Received-SPF: pass client-ip=195.110.48.8; envelope-from=mbork@mbork.pl; helo=mail.mojserwer.eu X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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:133553 Archived-At: On 2021-09-29, at 06:28, Emanuel Berg via Users list for the GNU Emacs text editor wrote: > Marcin Borkowski wrote: > >> Try this code. Make sure you set `lexical-binding' to t, >> e.g., by saving it to a file and visiting it again >> or something. >> >> ;;; -*- lexical-binding: t; -*- >> >> (setq global-lexical 24) >> >> (defun lexical-test () >> (message "%s" global-lexical)) >> >> (setq global-lexical 17) >> >> (lexical-test) >> >> (let ((global-lexical 12)) >> (lexical-test)) >> >> (defvar global-dynamic 24) >> >> (defun dynamic-test () >> (message "%s" global-dynamic)) >> >> (dynamic-test) >> >> (setq global-dynamic 17) >> >> (dynamic-test) >> >> (let ((global-dynamic 12)) >> (dynamic-test)) >> >> Can you spot the difference? Can you see why the dynamic one >> is better suited for options, i.e., you can temporarily set >> it with `let' and it Just Works? > > You mean options not from a human user, but an Elisp program > perspective? I.e., different subsystems use other subsystems > with their own set of options? Not sure if I understand. By an "option" I mean a variable I (the user) can set, either via `setq' (or customize) or via `let' (in my code) so that Emacs behavior is changed (temporarily in the case of `let'). > I guess that is/would be cool, in particular if it would work > in parallel ... > > Other than that, what I can see, you have provided the same > old example we have seen many times in slightly different > versions. It shows that lexical binding is less confusing and > less error-prone. It also shows the confusion that arises from > `let' because it not only behaves differently under lexical > binding and dynamic binding, it also behaves differently with > lexically and dynamically bound individual variables ... I wouldn't say "less confusing" - both lexical and dynamical binding serve their purposes, which are different. > Split up the `let' is what I think, into slet, `dlet' (which > already exists), and llet, an alias to `let' (or the other way > around, doesn't matter), which would be the same as our `let' > under lexical binding. Then remove all ugly preprocessor-style > ;;; -*- lexical-binding: t; -*- and everyone can just use > whatever they like with the different lets having their (and > only their) behavior in the docstrings, and that behavior > wouldn't change no matter any outside fiddling around. You mean you could use the same variable sometimes with `slet', sometimes with `dlet'? I'm not sure if that is easy or difficult to implement. Best, -- Marcin Borkowski http://mbork.pl