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!feeder.eternal-september.org!gandalf.srv.welterde.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.rrsoftware.com!not-for-mail From: "Randy Brukardt" Newsgroups: comp.lang.ada Subject: Re: discontinuous subtype without aspect Date: Tue, 30 Jan 2018 16:09:15 -0600 Organization: JSA Research & Innovation Message-ID: References: <6972f8eb-6130-4c47-b27a-f8dd0afeb171@googlegroups.com> Injection-Date: Tue, 30 Jan 2018 22:09:16 -0000 (UTC) Injection-Info: franka.jacob-sparre.dk; posting-host="rrsoftware.com:24.196.82.226"; logging-data="22744"; mail-complaints-to="news@jacob-sparre.dk" X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 X-RFC2646: Format=Flowed; Original X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.7246 Xref: reader02.eternal-september.org comp.lang.ada:50214 Date: 2018-01-30T16:09:15-06:00 List-Id: "Mehdi Saada" <00120260a@gmail.com> wrote in message news:6972f8eb-6130-4c47-b27a-f8dd0afeb171@googlegroups.com... >> ...because people didn't want set constraints. I still fail to understand >>why, as you point out, a static predicate is not quite a replacement. >It is a replacement, but I thought it was a shame there existed now, two >syntaxic > constructs to express the same things. They're not semantically the same thing, as the set of values for a type (determined by a constraint) is always contiguous. A predicate then excludes some values from the set for various purposes, but the formal value set of the type is always contiguous. I agree, though, that the difference is mainly semantic, but it does show in the values of 'First and 'Last for the subtype, and a few other places. ... >Is that what you mean by set constraints ? Something like that, I don't remember the proposed syntax. The main difference is that a set constraint did change the set of values - so 'First and 'Last would change. There's not much difference, so I suppose that some people thought that the predicate version was simpler. I never agreed, so I'm the wrong person to talk to about this topic! Randy.