From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Three questions about pcase for Stefan Date: Sat, 23 Jan 2016 10:36:33 -0500 Message-ID: References: <87r3h8zfd4.fsf@web.de> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1453563411 25252 80.91.229.3 (23 Jan 2016 15:36:51 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 23 Jan 2016 15:36:51 +0000 (UTC) Cc: Emacs Development To: Michael Heerdegen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jan 23 16:36:42 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aN0Ez-0003Bu-Pi for ged-emacs-devel@m.gmane.org; Sat, 23 Jan 2016 16:36:41 +0100 Original-Received: from localhost ([::1]:57776 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aN0Ey-0007Pj-Ut for ged-emacs-devel@m.gmane.org; Sat, 23 Jan 2016 10:36:40 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:56931) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aN0Ev-0007Pd-0P for emacs-devel@gnu.org; Sat, 23 Jan 2016 10:36:37 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aN0Er-0005W4-RR for emacs-devel@gnu.org; Sat, 23 Jan 2016 10:36:36 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:52201) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aN0Er-0005W0-ND for emacs-devel@gnu.org; Sat, 23 Jan 2016 10:36:33 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: A0AxFgA731xV/zh9oWxcgxCEAoVVu0CHSwQCAoE8OhMBAQEBAQEBgQpBBYNdAQEDAVYjBQsLNBIUGA0kiDcIzyMBAQEBBgEBAQEeizqFBQeELQWMMKcPgUUjhBYggngBAQE X-IPAS-Result: A0AxFgA731xV/zh9oWxcgxCEAoVVu0CHSwQCAoE8OhMBAQEBAQEBgQpBBYNdAQEDAVYjBQsLNBIUGA0kiDcIzyMBAQEBBgEBAQEeizqFBQeELQWMMKcPgUUjhBYggngBAQE X-IronPort-AV: E=Sophos;i="5.13,465,1427774400"; d="scan'208";a="190800792" Original-Received: from 108-161-125-56.dsl.teksavvy.com (HELO pastel.home) ([108.161.125.56]) by ironport2-out.teksavvy.com with ESMTP; 23 Jan 2016 10:36:33 -0500 Original-Received: by pastel.home (Postfix, from userid 20848) id 130C460164; Sat, 23 Jan 2016 10:36:33 -0500 (EST) In-Reply-To: <87r3h8zfd4.fsf@web.de> (Michael Heerdegen's message of "Sat, 23 Jan 2016 12:48:07 +0100") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.154.181 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:198649 Archived-At: > i.e., floats do not count as "atom". This is consistent, also explained > correctly in the doc, but may nonetheless be confusing. What led you to > this decision? Testing equality of floating point numbers is very rarely correct. > 2. Do you think we can already bury the old deprecated special behavior > of the atoms nil and t as patterns? Far from that. IIUC, it's even still used in a GNU ELPA package. We'll have to live with it for a reasonably long time. And to tell you the truth, I don't think it's a great idea to make nil and t match themselves. We can plan on making them signal errors, OTOH (for Emacs-26.1 or Emacs-27.1). > 3. Is it correct to say that not only the functions used in a pred > pattern, but any ordinary Lisp code part of any pattern (guard, app, > let, etc.) should be pure in the same sense? Yes. Stefan