From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: =?utf-8?Q?=C3=93scar_Fuentes?= Newsgroups: gmane.emacs.help Subject: Re: (*) -> 1 Date: Wed, 18 Jan 2023 15:07:10 +0100 Message-ID: <878ri09bsh.fsf@telefonica.net> References: <87sfg9kuya.fsf@web.de> <87bkmxkpzg.fsf@web.de> <878ri1av5j.fsf@telefonica.net> <87ilh4kgqo.fsf@web.de> <87zgagakh5.fsf@telefonica.net> <87cz7cka06.fsf@web.de> <87v8l49t8w.fsf@telefonica.net> <87h6wo9fjb.fsf@telefonica.net> <87edrsufdd.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="34009"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:QTF3sW1ZQYwJ5qwHkG816EcmOcU= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Jan 18 15:07:49 2023 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1pI96T-0008dj-AO for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 18 Jan 2023 15:07:49 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pI963-0008VM-TH; Wed, 18 Jan 2023 09:07:23 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pI962-0008Up-5m for help-gnu-emacs@gnu.org; Wed, 18 Jan 2023 09:07:22 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pI960-0006iA-Ez for help-gnu-emacs@gnu.org; Wed, 18 Jan 2023 09:07:21 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1pI95w-0007xo-Tr for help-gnu-emacs@gnu.org; Wed, 18 Jan 2023 15:07:16 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:142359 Archived-At: Michael Heerdegen writes: > Óscar Fuentes writes: > >> Even a programmer can't assume that associativity and commutativity >> can be used on a long, finite, sum. > > As long as it's a sum, of course can a programmer assume that. Of course not! Otherwise your numerical simulation can go very wrong :-) (hint: numbers in computers are approximate, adding small numbers to large numbers is a bad idea.) >> But that's a digression. My point is that (+) and (+ n) are not >> supported (or, better said, appreciated) because some mathematical >> reason, but because they are as much convenient when writing macros as >> they are silly on "normal" code. It's about making easy for the >> programmer to do some mundane tasks, not about Mathematics. > > No - the result of "1" is surely related to mathematics. It comes from > the mathematical interpretation of the term (*) as empty product. Sure. > You can interpret it differently, but the convention is the same and > there for the same reason as the same convention for the empty product > in math. Sure^2. I was talking about _why_ (*) and (* a) are supported in Elisp. Once the language designer chose to support those expressions and decided that they must return a number (instead of something else like a partially applied function) the value they shall return comes from the properties of the underlying operation, of course.