From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Leo Newsgroups: gmane.emacs.devel Subject: Re: Common Lisp like feature expressions Date: Tue, 28 Dec 2010 15:26:31 +0000 Message-ID: References: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: dough.gmane.org 1293550009 8594 80.91.229.12 (28 Dec 2010 15:26:49 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Tue, 28 Dec 2010 15:26:49 +0000 (UTC) Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Dec 28 16:26:45 2010 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PXbRl-0002o6-30 for ged-emacs-devel@m.gmane.org; Tue, 28 Dec 2010 16:26:45 +0100 Original-Received: from localhost ([127.0.0.1]:44019 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PXbRk-0000Ve-Dm for ged-emacs-devel@m.gmane.org; Tue, 28 Dec 2010 10:26:44 -0500 Original-Received: from [140.186.70.92] (port=39883 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PXbRe-0000VV-NF for emacs-devel@gnu.org; Tue, 28 Dec 2010 10:26:39 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PXbRd-0001es-Dg for emacs-devel@gnu.org; Tue, 28 Dec 2010 10:26:38 -0500 Original-Received: from mail-wy0-f169.google.com ([74.125.82.169]:42019) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PXbRd-0001eY-8T for emacs-devel@gnu.org; Tue, 28 Dec 2010 10:26:37 -0500 Original-Received: by wyj26 with SMTP id 26so9713967wyj.0 for ; Tue, 28 Dec 2010 07:26:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:from:to:cc:subject:references :date:in-reply-to:message-id:user-agent:mime-version:content-type; bh=4qNLx4WAAWFF5Zzx7KUM8FPEjEXCr7H/goprwvN/Klg=; b=NrYMnc0w8q4izZfbvVbOpPOzuAZ0IC5CL9c5wmgfQrszYblyblYiX64Jn/4kOT0Aeu kw61T6JY1rEo07xXZOcV9ahem1OctWO8CflBudC5yDoKEEfeIzjS5xxXLZclpFRV8cTK /2RSY7iT+svSL5/5ZBLGhua7ksW8KSrzbmDQY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version:content-type; b=lGt6RQjD1jdGk+MTyK7s1HlfiS2tWTqEMNYBrUeloEGDD2BEIUm2ctKQ21zHzk85gb gzmq6oIn5aKHr48GLtSzwxS2eXZP+2lzIUg8TSt9rCqBpOyzGyLR/lc1vlNxMMUP6BmH D1y4EP+T002wEoWCaSQSo8xRCb3mBax279doc= Original-Received: by 10.227.146.145 with SMTP id h17mr8025820wbv.60.1293549996026; Tue, 28 Dec 2010 07:26:36 -0800 (PST) Original-Received: from Victoria.local (cpc1-cmbg13-0-0-cust596.5-4.cable.virginmedia.com [86.9.122.85]) by mx.google.com with ESMTPS id 11sm9366079wbi.12.2010.12.28.07.26.33 (version=TLSv1/SSLv3 cipher=RC4-MD5); Tue, 28 Dec 2010 07:26:34 -0800 (PST) In-Reply-To: (Stefan Monnier's message of "Mon, 27 Dec 2010 20:01:02 -0500") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2.91 (Mac OS X 10.6.5) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:134005 Archived-At: On 2010-12-28 01:01 +0000, Stefan Monnier wrote: > Just for fun, here's a version using pcase: > > (defun eval-feature-expression (form) > (pcase form > ((pred atom) (featurep form nil)) > (`(not ,x) (not (eval-feature-expression x))) > (`(and) t) > (`(and ,form1 . ,forms) > (and (eval-feature-expression form1) > (eval-feature-expression (cons 'and forms)))) > (`(or) nil) > (`(or ,form1 . ,forms) > (or (eval-feature-expression form1) > (eval-feature-expression (cons 'or forms)))) > (t (error "Invalid feature expression: %s" form))))) That appears to be an excellent example for pcase. Maybe it should be added to the header of pcase.el or where it is documented? Thanks. Leo