From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: remove sublist Date: Mon, 02 Apr 2018 15:28:57 +0200 Organization: Aioe.org NNTP Server Message-ID: <86in99spnq.fsf@zoho.com> References: <86muylstcc.fsf@zoho.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1522675718 19492 195.159.176.226 (2 Apr 2018 13:28:38 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 2 Apr 2018 13:28:38 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon Apr 02 15:28:34 2018 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f2zVh-0004tw-H7 for geh-help-gnu-emacs@m.gmane.org; Mon, 02 Apr 2018 15:28:33 +0200 Original-Received: from localhost ([::1]:34977 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f2zXj-0005Wq-9n for geh-help-gnu-emacs@m.gmane.org; Mon, 02 Apr 2018 09:30:39 -0400 Original-Path: usenet.stanford.edu!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 57 Original-NNTP-Posting-Host: Mq3CdlVpWThKpW6fSn+6ow.user.gioia.aioe.org Original-X-Complaints-To: abuse@aioe.org Mail-Copies-To: never X-Notice: Filtered by postfilter v. 0.8.3 Cancel-Lock: sha1:87deUZ4a0a6FNCE4V0g4Vt+GMAI= Original-Xref: usenet.stanford.edu gnu.emacs.help:222191 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.help:116309 Archived-At: Yuri Khan wrote: > Maybe > > (cl-set-difference '("0" "a" "b" "c" "d") > '("a" "b") > :test 'string=) > > ? Excellent, thanks! You got the right idea, "sublist" as in the math unordered set sense - and not "set" as in the serpent god of the paleo-pharaohs, here! And items in the sublist that do not appear should be dropped, as happens. Should the test function be hash-quoted? Only strange thing is the order is reversed, except for the empty list as sublist! I just said it was in the unordered sense, however one might just as well keep the order, especially since even/particularly in the math unordered set sense, {1 2 3} = {3 2 1}, right? So it should work both ways; and it might be useful for example if you have a list of functions, (f1 f2 f3 f4), and it is a priority list so if f1 is defined, run it, if not, try/run f2, etc., here, if the user dislikes f2 and f3, but have them defined for other purposes, s/he can remove them from the list without changing the priority! However how is that supposed to be done? What about (defun drop-sublist (l sl) (if sl (reverse (cl-set-difference l sl :test #'string-equal)) l)) ;; (drop-sublist '("0" "a" "b" "c" "d") '("a" "b" "x")) ;; (drop-sublist '("0" "a" "b" "c" "d") '(x)) ;; (drop-sublist '("0" "a" "b" "c" "d") '()) ? It sort of goes against grain to reverse to *preserve* the order, but I suppose this is what makes programming an engineering and not a scientific endeavor... -- underground experts united http://user.it.uu.se/~embe8573