From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: How to delete all nil properties from a plist? Date: Sun, 02 Aug 2015 00:03:50 +0200 Message-ID: <87oaiq3buh.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1438466667 4076 80.91.229.3 (1 Aug 2015 22:04:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 1 Aug 2015 22:04:27 +0000 (UTC) To: Help Gnu Emacs mailing list Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sun Aug 02 00:04:17 2015 Return-path: Envelope-to: geh-help-gnu-emacs@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 1ZLet6-0004q0-Tn for geh-help-gnu-emacs@m.gmane.org; Sun, 02 Aug 2015 00:04:17 +0200 Original-Received: from localhost ([::1]:54806 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZLet6-0006dy-AO for geh-help-gnu-emacs@m.gmane.org; Sat, 01 Aug 2015 18:04:16 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53922) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZLesv-0006Zl-RE for help-gnu-emacs@gnu.org; Sat, 01 Aug 2015 18:04:06 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZLesq-0005xl-SE for help-gnu-emacs@gnu.org; Sat, 01 Aug 2015 18:04:05 -0400 Original-Received: from mail.mojserwer.eu ([2a01:5e00:2:52::8]:56503) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZLesq-0005wo-L1 for help-gnu-emacs@gnu.org; Sat, 01 Aug 2015 18:04:00 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id CED178F2008 for ; Sun, 2 Aug 2015 00:03:59 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bBipTMAy8Jah for ; Sun, 2 Aug 2015 00:03:57 +0200 (CEST) Original-Received: from localhost (unknown [109.232.24.146]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 340568F2002 for ; Sun, 2 Aug 2015 00:03:57 +0200 (CEST) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a01:5e00:2:52::8 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:106193 Archived-At: Hi all, so I'm still using plists, though I'm less and less sure that they are actually better than alists for my use-case. Now I need to delete all properties whose value is nil. I'm using this function: --8<---------------cut here---------------start------------->8--- (defun plist-clear (plist) "Return PLIST with all nil properties deleted." (cond ((< (length plist) 2) nil) ((null (cadr plist)) (cddr plist)) (t (cons (car plist) (cons (cadr plist) (plist-clear (cddr plist))))))) --8<---------------cut here---------------end--------------->8--- Question 1: is there a better way to write it? (Especially the last line.) Question 2: how would I do the analogous thing with alists? TIA, -- Marcin Borkowski http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski Faculty of Mathematics and Computer Science Adam Mickiewicz University