From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.bugs Subject: bug#34852: 26.1; seq-intersection ignores nil as element Date: Thu, 14 Mar 2019 22:40:27 -0400 Message-ID: References: <87zhpxabn3.fsf@tcd.ie> <87va0lmwlg.fsf@web.de> <8736np58gg.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="145751"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) Cc: "Basil L. Contovounesios" , Nicolas Petton , 34852@debbugs.gnu.org, "Miguel V. S. Frasson" To: Michael Heerdegen Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Fri Mar 15 03:52:06 2019 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1h4cx1-000bkS-LR for geb-bug-gnu-emacs@m.gmane.org; Fri, 15 Mar 2019 03:52:03 +0100 Original-Received: from localhost ([127.0.0.1]:48247 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h4cx0-0006Ii-Mm for geb-bug-gnu-emacs@m.gmane.org; Thu, 14 Mar 2019 22:52:02 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:38439) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h4cwp-0006C8-T9 for bug-gnu-emacs@gnu.org; Thu, 14 Mar 2019 22:51:52 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h4cmM-0001i6-Sm for bug-gnu-emacs@gnu.org; Thu, 14 Mar 2019 22:41:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:58970) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1h4cmM-0001hz-NH for bug-gnu-emacs@gnu.org; Thu, 14 Mar 2019 22:41:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1h4cmM-0001jW-F5 for bug-gnu-emacs@gnu.org; Thu, 14 Mar 2019 22:41:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 15 Mar 2019 02:41:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 34852 X-GNU-PR-Package: emacs Original-Received: via spool by 34852-submit@debbugs.gnu.org id=B34852.15526176366620 (code B ref 34852); Fri, 15 Mar 2019 02:41:02 +0000 Original-Received: (at 34852) by debbugs.gnu.org; 15 Mar 2019 02:40:36 +0000 Original-Received: from localhost ([127.0.0.1]:44281 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1h4clw-0001ii-Hy for submit@debbugs.gnu.org; Thu, 14 Mar 2019 22:40:36 -0400 Original-Received: from chene.dit.umontreal.ca ([132.204.246.20]:59850) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1h4clq-0001iW-JN for 34852@debbugs.gnu.org; Thu, 14 Mar 2019 22:40:35 -0400 Original-Received: from pastel.home (lechon.iro.umontreal.ca [132.204.27.242]) by chene.dit.umontreal.ca (8.14.7/8.14.1) with ESMTP id x2F2eSrG017513; Thu, 14 Mar 2019 22:40:28 -0400 Original-Received: by pastel.home (Postfix, from userid 20848) id 01E086AB89; Thu, 14 Mar 2019 22:40:27 -0400 (EDT) In-Reply-To: <8736np58gg.fsf@web.de> (Michael Heerdegen's message of "Fri, 15 Mar 2019 00:42:39 +0100") X-NAI-Spam-Flag: NO X-NAI-Spam-Threshold: 5 X-NAI-Spam-Score: 0 X-NAI-Spam-Rules: 2 Rules triggered EDT_SA_DN_PASS=0, RV6503=0 X-NAI-Spam-Version: 2.3.0.9418 : core <6503> : inlines <7034> : streams <1815736> : uri <2812972> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.51.188.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:156368 Archived-At: >> > (seq-contains nil '(nil t foo) (lambda (x) t)) -> nil >> > It returns *nil* if testfn fails, or *nil* (ELT) if it succeds. >> Just because it sometimes does doesn't mean it always does: >> (seq-contains '(0 3 4) 1 #'<) >> returns 3 > Maybe it's too late here, but why is that a counterexample for >> If ELT=nil, seq-contains currently returns nil anyway;" Duh, sorry, I lost sight of the goal along the way. A short real counter example is (seq-contains '(1) nil #'list) but it's admittedly contrived. A more real counter example is the one alluded to by Nicolas earlier: (seq-contains '((t 1) (nil 2)) nil (lambda (x y) (equal x (car y)))) > The first element is returned for that the test succeeds, what's special > about it? < is not symmetrical, though, so it's a weird kind of > equality test. The test doesn't need to be an equality test. IOW seq-contains is very close to seq-find. Stefan