From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.help Subject: Re: (*)->1 Date: Sat, 14 Jan 2023 13:03:33 +0100 Message-ID: <87tu0tjpbe.fsf@web.de> References: <61c2cc81db661e2624771a06a1274eac.support1@rcdrun.com> <87y1qdct5m.fsf@gnu.org> <874jt0imh0.fsf@dataswamp.org> <875ydeas0w.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="22468"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Jan 14 13:04:15 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 1pGfGg-0005ck-GN for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 14 Jan 2023 13:04:14 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pGfGA-0001S1-N7; Sat, 14 Jan 2023 07:03:42 -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 1pGfG7-0001Ra-0K for help-gnu-emacs@gnu.org; Sat, 14 Jan 2023 07:03:39 -0500 Original-Received: from mout.web.de ([212.227.17.12]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pGfG5-0003he-6c for help-gnu-emacs@gnu.org; Sat, 14 Jan 2023 07:03:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=s29768273; t=1673697814; bh=YWb4ByHR/Y2E1lWyrKthGqVxvXeZcBx2K0vJxJzczMA=; h=X-UI-Sender-Class:From:To:Subject:In-Reply-To:References:Date; b=QAiL/6jqvQzxDuYrWh/gRowdlSfXxSR7+lQC43vL/faAb2NPEvmjuo/PiwI0BAih1 v+W6q8QJ05zXzjhl6stm9wz8MYYEq7EPlhK/fUKCrQEoseP/HH0MDKpoYEdUkev7Ze gDq1rJ0KunGG+NzGB2sEICfgcO0+I0P0nEpYgzPY77Rdk1ZQUXdCZi3LhPobQsgdq4 Q9sPI8Rdl/zbDRRQAMMPXx8PUX1NIv99PCz3JOr21RQZF0uWEns8mv2fwrXpZWnKOb O8OqLqAezQ07/GlZfBUsMhRNgh3c49v23C4i8vUFCnTMHgeNgSGEaKaymHk5kDEglq 8+3ZjDM5T+Uvw== X-UI-Sender-Class: 814a7b36-bfc1-4dae-8640-3722d8ec6cd6 Original-Received: from drachen.dragon ([84.59.210.57]) by smtp.web.de (mrweb105 [213.165.67.124]) with ESMTPSA (Nemesis) id 1Mvbiu-1oQLsu07mA-00swmC; Sat, 14 Jan 2023 13:03:34 +0100 In-Reply-To: (Jean Louis's message of "Fri, 13 Jan 2023 09:21:53 +0300") X-Provags-ID: V03:K1:otJ6TnaaTzzyfim347nb1RmMyLCOOEt94K5506iudqq/dJy6V+e k25X8qb7cwRMFAMPneEXQY1BBPOYzAj49HNm+AkQYB0Y9SXuwGt9IYvX4OVcTRyqOJdPB10 DjY1tHoLPC0tKdLK2s+zypVc+9b7IrmOP/nglov9Gk4JU8sSx8QrS0PQ1H7UJeBD0MdnITe IJ5ntHi3mFyRShPtKZZbg== UI-OutboundReport: notjunk:1;M01:P0:Ko4pZiDZChs=;SHhDg0JXUH8J9oZv4pPI2TbFerW +EdJIPcRWdkUpMdo3jlJI1PmSuSsbw44sHwkZ5hSuvnbz8WGck/OrnHKGfSWCyiAqZv3zD3yx vBHZRIgv8DShsQOLZluLK6a5Fdcllu1xz6J7F9omeXiDSYiSTxTPtIeW+ZyNNWT1GeC3ScwXH 6izcRJK0gHQBAk7A8kfGHm8f+psN9MV9pfOEsf7GMSKMQ0wuSRWi47MQLNZ+A7ukFHflQF58O f3VnPyYR73jwcFyHvTNOPSVPL0fArRH9WLt4wNF1CQNrLOqVKS1qPcapCyTepRrvunrXnbySr MkemC0NKhKsfNY6P/LvylQJjPPiquHkiiKsq2r+sEbWTubfO/gpkJ7V4H+lDo+WW/41SH+q0E VKjNsgK+98b/7O0JDUUiopv8jyOvUWWkFySajWPoZPtS3B+cYUjca2zZaIqXpZnBvQmI9x0ji FbCjYulsIPpwqswviq/UyOpjdL78as5UWwsz8YIOOBT6vQA3Y4aIODXUFKXfM3lcuGw2oMXqE y0McB2d8ylMRXuotR9B4rP6n9zmrXj2CMRKaokhdBuMK9UlRFJ7lCoaby6X24srteNKScC/40 7xwp+RRAuoJKh/llaM/34abPaOBhJjq1m99LPLWqlwXKzUNi3VKzHZ++mfte2rhAp8+/rW9bQ HHGaytSSH0YrS9A0d96pRU8PKfj7sm5YawEFs1J1JqQm/axkC2ef2ovQy0NQyZ3CmqfffrE5e 2ccsGWtc6I0VQ2kb7jQp32HvjSbPur0SxatRj2sm73a4HtlsMS/KWSccdeCaf/px+Bklrx2d Received-SPF: pass client-ip=212.227.17.12; envelope-from=michael_heerdegen@web.de; helo=mout.web.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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:142234 Archived-At: Jean Louis writes: > Thus (+) =E2=9E=9C 0 without value result should not be zero. If no values > where given to addition, no addition has taken place. Value of zero > should not get out of nothing. Mathematically it is neither right nor wrong. It is a convention to assign 0 to an empty sum. This is for convenience, and it doesn't lead to contradictions. It is convenient because if you decompose a sum into partial sums, equations remain correct for the corner case of empty partial sums: then the contribution of an empty partial sum to the whole sum is 0. Likewise for products and other operations. This convention is used in whole mathematics because it elegantly avoids case distinctions. It's also a useful convention in programming. For example, the initial value of an accumulator of a sum calculation is 0. If you sum up partial sums it would be nonsense to assign a special value for empty partial sums that behaves like 0 but means 0_{from zero summands}. We also don't have 7_{from 3 summands} we just have 7. The number of summands doesn't matter if you are interested in a sum, even when the number of summands is zero. Note that nobody will ever use the expression (+) directly to find 0 to try to learn something from it. But the case may appear in calculations like e.g. (apply #'+ args) and such where an empty arg list might appear. Some other perspective: when you play a video game and got no rewarded actions before game over, your score is typically 0. You could also get "void game" or no entry in the high score list. As I said, it's a mathematical convention, you can't derive something wrong from it, it's just convenient. We could make (+) error or emit something new but that would just make Elisp worse. Michael.