From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.bbs-scene.org!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Mon, 08 Jul 2013 18:18:47 -0500 Date: Mon, 08 Jul 2013 19:18:47 -0400 From: "Peter C. Chapin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: The future of Spark . Spark 2014 : a wreckage References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-lzH5vP2O+j7HZy1hJ/yee4JUsewUEMkiicjv6W4h/rdn2pb4WMkotSKMCN8SVwYAhrxKoY61gryp9L7!qIixbvv2NJ1oLVbn44upvPrN8eddLXVq+cIc1lLA/IwG1C3p9e/5XIL9PZ4SiYs= X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2558 Xref: news.eternal-september.org comp.lang.ada:16178 Date: 2013-07-08T19:18:47-04:00 List-Id: On 07/08/2013 01:56 PM, vincent.diemunsch@gmail.com wrote: > procedure Swap > with Global => (In_Out => (X, Y)), > Depends => (X => Y, -- to be read as "X depends on Y" > Y => X); -- to be read as "Y depends on X" > > How are we supposed to guess that "X => Y" means X depends on Y, if the arrow goes from X to Y ? Well the phrase "X depends on Y" has X on the left and Y on the right just as X => Y does. So it reads fairly naturally to me. I understand there is value in being consistent with existing notations although I get the impression there is already conflicting practice in that area. More significantly, though, I think you may be assigning too much semantic weight to the '=>' token in this case. In the aspect syntax it is used more as a separator than anything else. Consider Pre => X < 0 Nobody would say that there is information flowing from "Pre" to the expression 'X < 0' or visa-versa. The SPARK 2014 syntax extends this notion of "arrow as separator" to the subcomponents of the aspects. Thus Depends => (X => Y) The "inner" arrow just separates X from Y syntactically. It's not really related to information flow... although its easy to see why someone would assume that it was considering the semantics of the Depends aspect overall. Peter