From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Helmut Eller Newsgroups: gmane.emacs.devel Subject: Re: named-let Date: Sat, 09 Jan 2021 18:03:54 +0100 Message-ID: References: <87im86kub6.fsf@logand.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31019"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: emacs-devel@gnu.org Cancel-Lock: sha1:4Ai0diVr9ZZnmE9d/x2Jfct1xLQ= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Jan 09 18:05:00 2021 Return-path: Envelope-to: ged-emacs-devel@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 1kyHfg-0007uV-67 for ged-emacs-devel@m.gmane-mx.org; Sat, 09 Jan 2021 18:05:00 +0100 Original-Received: from localhost ([::1]:60522 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kyHff-0000Ff-8a for ged-emacs-devel@m.gmane-mx.org; Sat, 09 Jan 2021 12:04:59 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:38094) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kyHem-0007q3-Ny for emacs-devel@gnu.org; Sat, 09 Jan 2021 12:04:04 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:41010) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kyHel-0002BI-Cn for emacs-devel@gnu.org; Sat, 09 Jan 2021 12:04:04 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kyHej-0006Wu-Ny for emacs-devel@gnu.org; Sat, 09 Jan 2021 18:04:01 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=ged-emacs-devel@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIM_ADSP_CUSTOM_MED=0.001, FORGED_GMAIL_RCVD=1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.25, NML_ADSP_CUSTOM_MED=0.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:262809 Archived-At: On Sat, Jan 09 2021, Stefan Monnier wrote: >> Is TCO always used (like in Scheme) or in which cases is it used or not used? > > It's basically never used. It's only applied for the particular case of > tail recursive calls to functions defined by `cl-labels` and only for > those calls that are "self-recursive" (i.e. come from within the code of > that function). Is there hope for general contification? So that things like (defun my-even? (x) (cl-labels ((even? (x) (or (= x 0) (odd? (1- x)))) (odd? (x) (or (= x 1) (even? (1- x))))) (even? x))) are translated to a bunch of gotos and no lambdas. Helmut