From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Compiling a recursive macro Date: Thu, 11 Jun 2020 16:57:05 -0400 Message-ID: References: <22b55d6d-f719-98d9-f8c8-e72e7fc43497@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="1107"; 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:ZHfAdSOMpKhYBogNc97sSGyLCLU= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Thu Jun 11 22:58:13 2020 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 1jjUH6-0000Bz-UZ for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 11 Jun 2020 22:58:12 +0200 Original-Received: from localhost ([::1]:37910 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jjUH5-0001Sb-Uz for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 11 Jun 2020 16:58:11 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:33304) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jjUGC-0001Qn-9g for help-gnu-emacs@gnu.org; Thu, 11 Jun 2020 16:57:16 -0400 Original-Received: from ciao.gmane.io ([159.69.161.202]:49922) by eggs.gnu.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jjUGA-00087p-6l for help-gnu-emacs@gnu.org; Thu, 11 Jun 2020 16:57:15 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1jjUG8-000WxD-0u for help-gnu-emacs@gnu.org; Thu, 11 Jun 2020 22:57:12 +0200 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=159.69.161.202; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/11 16:57:12 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -8 X-Spam_score: -0.9 X-Spam_bar: / X-Spam_report: (-0.9 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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:123335 Archived-At: > That suggests to me that you can't compile any recursive macro. Depends what you mean by "recursive macro". What this prevents is to use a macro inside the definition of a macro. Most cases of "recursive macros" instead just returns code which itself uses that macro. In that case, there's no real recursion: the macro just returns a list which happens to include a symbol which has the same name as the macro. And then the macro-expander will end up calling that macro back when it gets to macro-expanding that chunk of code. This works just fine (and may inf-loop, of course). Stefan