From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.5-pre1 Path: eternal-september.org!reader02.eternal-september.org!aioe.org!5WHqCw2XxjHb2npjM9GYbw.user.gioia.aioe.org.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: array from static predicate on enumerated type Date: Sat, 13 Mar 2021 09:04:51 +0100 Organization: Aioe.org NNTP Server Message-ID: References: <89128f73-fcc5-4e57-8067-d09877ba0211n@googlegroups.com> <6ca041f3-2669-4497-9548-2f17666702a6n@googlegroups.com> NNTP-Posting-Host: 5WHqCw2XxjHb2npjM9GYbw.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader02.eternal-september.org comp.lang.ada:61509 List-Id: On 2021-03-13 03:06, Matt Borchers wrote: > I pretty much agree with Dmitry on this. The usefulness of this is very, very low without better support from the language itself. However, Dmitry, if programmers should not consider a feature of a language as an option for a solution, then it begs the question on the quality of the language, quality of the compiler, or questions the abilities of caretakers of Ada. Don't get me wrong, however, I think Ada is exceptional. Subtyping is a very difficult problem. When a new type is created by constraining [*] this necessarily breaks things. Ada 83 was very careful to limit that to ranges and discriminant values. That breaks, sure, but the damage is minor and can be controlled [by the programmer]. In contrast, an arbitrary constraint [as well as arbitrary extension] is like a carpet bombing. My view, as a programmer, is that features of type algebra [which subtyping by constraining is] must be carefully limited to enable massive language support in detection of substitutablity issues at *compile* time. Features must be reasonably safe to use. ---------------------------------- * Sorry, guys, Ada subtypes are types. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de