Path: csiph.com!usenet.pasdenom.info!dedibox.gegeweb.org!gegeweb.eu!nntpfeed.proxad.net!proxad.net!feeder1-2.proxad.net!usenet-fr.net!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.010 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'subject:Python': 0.05; 'mutable': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'terry': 0.09; 'collections.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'worlds,': 0.16; 'wrote:': 0.17; 'mathematical': 0.17; 'jan': 0.18; 'defined': 0.22; 'programming': 0.23; 'sets': 0.23; 'least': 0.25; 'header :In-Reply-To:1': 0.25; 'header:User-Agent:1': 0.26; 'am,': 0.27; 'header:X-Complaints-To:1': 0.28; 'doubt': 0.33; 'problem': 0.33; 'to:addr:python-list': 0.33; 'doing': 0.35; 'there': 0.35; 'received:org': 0.36; 'be.': 0.36; 'functional': 0.36; 'level.': 0.36; 'does': 0.37; 'subject:: ': 0.38; 'fact': 0.38; 'mean': 0.38; 'things': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'think': 0.40; 'real': 0.61; 'course.': 0.62; 'life,': 0.62; 'necessarily': 0.63; 'state,': 0.65; 'physical': 0.69; 'andrea': 0.84; 'received:fios.verizon.net': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: Immutability and Python Date: Mon, 29 Oct 2012 13:48:23 -0400 References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-173-75-251-66.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120824 Thunderbird/15.0 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 15 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1351532928 news.xs4all.nl 6968 [2001:888:2000:d::a6]:55227 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:32409 On 10/29/2012 11:20 AM, andrea crotti wrote: > I have a philosofical doubt about immutability, that arised while doing > the SCALA functional programming course. In real life, the physical world, things have mutable state, at least down to the atomic level. Do you only want to model mathematical worlds, or also physical worlds. Even mathematically, I do not think there necessarily a problem with mutable collections. The fact that sets are defined by content does not mean that everything has to be. -- Terry Jan Reedy