From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Drew Adams Newsgroups: gmane.emacs.devel Subject: RE: 7 logical-xor implementations in source tree Date: Wed, 31 Jul 2019 14:38:01 -0700 (PDT) Message-ID: <4de86e2c-18ab-4cf1-9a70-e43310234ad0@default> References: <87tvbd9a8p.fsf@oremacs.com> <87pnm14u95.fsf@tcd.ie> <87sgqvoz5c.fsf@tcd.ie> <87d0hz2e11.fsf@tcd.ie> <5B633129-B795-4BFA-AE81-FE9FD0A24CE9@acm.org> <0edfffbb-6f5a-a6b2-334a-9000e8f2eb3e@gmail.com> <20190728080417.GA5072@ACM> <875znm3q19.fsf@mbork.pl> <20190730093651.GA5427@ACM> <7n36iny4yq.fsf@ecube.ecubist.org> <7nftmmkz83.fsf@ecube.ecubist.org> <87y30e6j5b.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="172578"; mail-complaints-to="usenet@blaine.gmane.org" Cc: emacs-devel@gnu.org To: Michael Heerdegen , Barry Fishman Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Jul 31 23:38:19 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hswId-000il2-2f for ged-emacs-devel@m.gmane.org; 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Wed, 31 Jul 2019 21:38:04 GMT Original-Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2u349darq0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 31 Jul 2019 21:38:04 +0000 Original-Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x6VLc2qG031282; Wed, 31 Jul 2019 21:38:02 GMT In-Reply-To: <87y30e6j5b.fsf@web.de> X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 2.0.1.9.1 (1003210) [OL 16.0.4873.0 (x86)] X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9335 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=876 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907310216 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9335 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=928 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907310215 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 156.151.31.86 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.org gmane.emacs.devel:239067 Archived-At: I don't understand what all the excitement about defining an `xor' (with whatever name) operator is about. Common Lisp, like Emacs Lisp, has a bit-wise xor operator. That makes sense - useful. And Common Lisp, like Emacs Lisp, does _not_ have an xor operator for arbitrary Lisp values. https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node75.html Why is it important that Emacs Lisp have such an operator? (Answer: it's not - YAGNI.) Is it hard to understand (eq (not a) (not b))? Is evaluation of that inefficient? Is it too verbose? What's the motivation for all of this? My vote's against adding any such operator.