From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on ip-172-31-65-14.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 Path: eternal-september.org!reader01.eternal-september.org!aioe.org!gz+JwLUglqIuIsOsQSSzqA.user.46.165.242.91.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: New aggregates with Ada 2022. Date: Thu, 30 Jun 2022 10:44:17 +0200 Organization: Aioe.org NNTP Server Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: gioia.aioe.org; logging-data="2053"; posting-host="gz+JwLUglqIuIsOsQSSzqA.user.gioia.aioe.org"; mail-complaints-to="abuse@aioe.org"; User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader01.eternal-september.org comp.lang.ada:64059 List-Id: On 2022-06-30 07:03, Randy Brukardt wrote: > "Dmitry A. Kazakov" wrote in message > news:t9h4i9$118a$1@gioia.aioe.org... > ... >>> A language that provided direct support for these abstractions should not >>> need to provide arrays. >> >> Which is of course impossible considering the variety of maps (e.g. graph >> is a map etc) and all problem-space specific. > > Nobody uses arrays to implement graphs anyway. It depends on the type of graph and operations on it, high-connectivity graphs (incidence matrix) or b-trees (blocks) certainly would use arrays. > That's something you do when > you are using a language like Fortran 66 that doesn't have any abstractions. But that is unrelated to abstraction. FORTRAN had no access types therefore memory management of graph nodes was user-implemented on top of large arrays with the array index playing the role of a pointer to the node. Even if FORTRAN had abstract data types, in order to implement a graph datatype you would still have to resort to arrays. It is just different things: abstraction does not mean you have it implemented and conversely. In Ada we have array implementation, but very limited abstraction of: 1. formal generic arrays 2. definite/indefinite unification Index and aggregate hacks in no way support or extend the abstraction as the OP noticed. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de