From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Pascal J. Bourguignon" Newsgroups: gmane.emacs.help Subject: Re: no empty (zero) string predicate in Elisp Date: Sun, 26 Apr 2015 17:03:01 +0200 Organization: Informatimago Message-ID: <87oambhqze.fsf@kuiper.lan.informatimago.com> References: <87h9s4rhx5.fsf@debian.uxu> <87wq0zkqxa.fsf@debian.uxu> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1430061323 19185 80.91.229.3 (26 Apr 2015 15:15:23 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 26 Apr 2015 15:15:23 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sun Apr 26 17:15:19 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 1YmOH8-00080w-9k for geh-help-gnu-emacs@m.gmane.org; Sun, 26 Apr 2015 17:15:18 +0200 Original-Received: from localhost ([::1]:51081 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YmOH7-00079O-CY for geh-help-gnu-emacs@m.gmane.org; Sun, 26 Apr 2015 11:15:17 -0400 Original-Path: usenet.stanford.edu!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 45 Original-X-Trace: individual.net d4EWV0RkVjTOrq0aMzpB4Ah86HZa/LWVJKVIStSqasov+bdx8d Cancel-Lock: sha1:ZDIwY2ViYzVmNjY3YjAxMTRmOTI5YmUwNmIwYWQ3MjM1ZTlhYWE2MA== sha1:dO90o+Tq0+K8TEP77xN+7gQXHx4= Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Original-Xref: usenet.stanford.edu gnu.emacs.help:211722 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:104004 Archived-At: Emanuel Berg writes: >> not higher-level either > > I don't know the scientific definition of "high-level" > - or how it applies to these three Elisp functions. > > The reason I want a binary operator is that it is more > intuitive: it refects my way of thinking - "is the > string empty?" vs. "is the string equal to another > string that is empty?" - also, because a binary > operator reduces the number of data items in the code > (with one, the empty string). The only problem with that, is that a binary operator has 2 arguments: (binop a b) therefore if you want a binary operator, you want: (string= s "") On the other hand, if you want only one argument, then you want a unary operator: (unary a) and when this unary operator returns a boolean, you call it a predicate: (emptyp s) > In general, I don't want the same function to be > spelled out over and over to do the same thing - > instead, I want it factored out, named, and invoked > with a "minimal", that is, sufficient, interface. Definitely. -- __Pascal Bourguignon__ http://www.informatimago.com/ “The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment.” -- Carl Bass CEO Autodesk