Path: csiph.com!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!newsfeed.eweka.nl!eweka.nl!feeder3.eweka.nl!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!newsgate.cistron.nl!newsgate.news.xs4all.nl!194.109.133.84.MISMATCH!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!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 0.006 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'example:': 0.03; 'flows': 0.07; '[0,': 0.09; '[0]': 0.09; 'definitions.': 0.09; 'from:addr:python': 0.09; '[2,': 0.16; 'disregard': 0.16; 'from:addr:mrabarnett.plus.com': 0.16; 'from:name:mrab': 0.16; 'message-id:@mrabarnett.plus.com': 0.16; 'received:84.92': 0.16; 'received:84.92.122': 0.16; 'received:84.92.122.60': 0.16; 'reply- to:addr:python-list': 0.16; 'subject:programming': 0.16; 'this:': 0.16; 'wrote:': 0.18; 'trying': 0.21; 'header:In-Reply-To:1': 0.22; 'implicit': 0.23; 'work.': 0.27; 'skip:[ 10': 0.27; 'explicit': 0.29; 'cases.': 0.30; 'equivalent': 0.31; 'there': 0.33; "won't": 0.33; 'header:User-Agent:1': 0.33; 'rules': 0.34; 'received:84': 0.34; 'reply-to:addr:python.org': 0.34; 'to:addr :python-list': 0.35; 'however,': 0.35; 'two': 0.36; 'but': 0.37; 'either': 0.37; 'some': 0.38; 'think': 0.38; 'non': 0.38; 'to:addr:python.org': 0.40; 'more': 0.61; 'your': 0.61; 'therefore,': 0.68; 'header:Reply-To:1': 0.70; 'reply-to:no real name:2**0': 0.72; 'stream': 0.77; 'communicate,': 0.84; 'nathan': 0.84; 'streams': 0.84 X-CM-Score: 0.00 X-CNFS-Analysis: v=2.0 cv=Dp/UCRD+ c=1 sm=1 a=0nF1XD0wxitMEM03M9B4ZQ==:17 a=qePWxsfFzlIA:10 a=OUOv7kDek9cA:10 a=8nJEP1OIZ-IA:10 a=aXwN2fR8gm82CRp9INgA:9 a=wPNLvfGTeEIA:10 a=rtiCEioeswrPv96u:21 a=U9yz7XJ35L9l0Ssq:21 a=0nF1XD0wxitMEM03M9B4ZQ==:117 X-AUTH: mrabarnett:2500 Date: Fri, 23 Mar 2012 18:00:44 +0000 From: MRAB User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: python-list@python.org Subject: Re: Stream programming References: <4f6c9e17$0$1383$4fafbaef@reader2.news.tin.it> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list Reply-To: python-list@python.org 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: 40 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1332525634 news.xs4all.nl 6957 [2001:888:2000:d::a6]:46537 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:22090 On 23/03/2012 16:33, Nathan Rice wrote: >> I will use "<=>" to mean "is equivalent to". That's not part of the DSL. >> A flow has one or more streams: >> 1 stream: >> [1,2,3] >> 2 streams: >> [1,3,5] | [2,4,6] >> Two flows can be concatenated: >> [1,2,3] + [4,5,6]<=> [1,2,3,4,5,6] >> [0] + ([1,2] | [3,4]) + [10]<=> [0,1,2,10] | [0,3,4,10] >> ([1,2] | [10,20]) + ([3,4] | [30,40])<=> [1,2,3,4] | [10,20,30,40] > > Algebraically, your concatenation rules don't really make sense - your > flows are both distributive and non distributive. You also make the > implicit assumption of an order over streams in a flow, but disregard > the implications of that assumption in some cases. I understand what > you're trying to communicate, so I think you need to be a little more > strict and explicit in your definitions. > When concatenating, either there are the same number of streams, or one of them is a single stream which is duplicated. Therefore, in this example: [0] + ([1, 2] | [3, 4]) you're concatenating a single stream with a pair, so the single stream is duplicated: ([0] | [0]) + ([1, 2] | [3, 4]) and then they can be concatenated: ([0, 1, 2] | [0, 3, 4]) However, this: ([0, 1] | [2, 3]) + ([4, 5] | [6, 7] | [8, 9]) won't work.