From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Tomas Hlavaty Newsgroups: gmane.emacs.devel Subject: Re: Instead of pcase Date: Tue, 12 Dec 2023 20:24:46 +0100 Message-ID: <87fs072phd.fsf@neko.mail-host-address-is-not-set> References: <87fs169mjj.fsf@posteo.net> <093f11a1-57c2-5e56-d39b-26fef1c67cbb@gutov.dev> <25942.25061.217864.329049@retriever.mtv.corp.google.com> <87zfzdcz6z.fsf@posteo.net> <87zfza2aq2.fsf@web.de> <7nmsv9zq6u.fsf@ecube.ecubist.org> <7nv89x5tsi.fsf@ecube.ecubist.org> <87o7focuf5.fsf@web.de> <875y1r10jr.fsf@web.de> <87v895iyzy.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="7773"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: rms@gnu.org, Michael Heerdegen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Dec 12 20:25:54 2023 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 1rD8O9-0001rM-3S for ged-emacs-devel@m.gmane-mx.org; Tue, 12 Dec 2023 20:25:53 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rD8NC-0006yh-TD; Tue, 12 Dec 2023 14:24:54 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rD8NA-0006yK-Ip for emacs-devel@gnu.org; Tue, 12 Dec 2023 14:24:52 -0500 Original-Received: from logand.com ([37.48.87.44]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rD8N9-0001Tg-1M; Tue, 12 Dec 2023 14:24:52 -0500 Original-Received: by logand.com (Postfix, from userid 1001) id 1523019E83F; Tue, 12 Dec 2023 20:24:49 +0100 (CET) X-Mailer: emacs 28.2 (via feedmail 11-beta-1 I) In-Reply-To: Received-SPF: pass client-ip=37.48.87.44; envelope-from=tom@logand.com; helo=logand.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:313730 Archived-At: in plain lisp with much clearer control-flow (not tested): (defun byte-optimize-letX (form) (if (consp form) (let ((head (car form)) (bindings (cadr form)) (body (cddr form))) (if bindings (let ((const (car body)) (rest (cdr body))) (if (or (not body) (and (macroexp-const-p const) (not rest))) ;; Body is empty or a constant. (if (eq head 'let) `(progn ,@(mapcar #'cadr bindings) ,const) `(,head ,(butlast bindings) ,(cadar (last bindings)) ,const)) (if (let ((last-var (car-safe (car (last bindings))))) (and (symbolp last-var) (equal body (list last-var)))) ;; Body does nothing but return the last variable in bindings. (if (eq head 'let) `(progn ,@(mapcar #'cadr bindings)) `(,head ,(butlast bindings) ,(cadar (last bindings)))) form)) ;; Bindings list is empty. `(progn ,@body))) form)))