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: Lower bounds of Strings Date: Tue, 19 Jan 2021 23:27:28 +0100 Organization: Aioe.org NNTP Server Message-ID: References: <1cc09f04-98f2-4ef3-ac84-9a9ca5aa3fd5n@googlegroups.com> <6450332c-89a8-476d-a112-c98b8bb08009n@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/78.6.1 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader02.eternal-september.org comp.lang.ada:61174 List-Id: On 2021-01-19 22:02, G.B. wrote: > On 14.01.21 16:41, Dmitry A. Kazakov wrote: >> >> That would be a sequential access interface. A common sequence as in >> mathematics has nth-element random access on top of it. > > Mathematical sequences are not real. Their description is: Nope, only mathematics is real, the rest is fiction! (:-)) > The finite variants are tuples. Component access is "at random". > The infinite variants tend to be construed so that randomness is a > useful fiction; The term is countable infinite. Note the word countable, that guaranties that each element has an integer number, ergo randomly accessed by this number. > a program can access an element if successors are produced one by one. > Order exists only after the fact. Order exists per definition of sequential access. More constrained interfaces could be sequences that cannot be enumerated backwards. E.g. there is Sequence.Next, but no Sequence.Previous, e.g. a queue end's interface. > The other sequences cannot be computed for the most part. > > So, therefore, with regard to what should characterize sequences in > programming, I find sequential access to be the defining feature. Nope. That is no feature, that is an *interface* with certain operations, like Next and Previous. This interface inherits the one-way interface. Array interface inherits both and defines further operations. This is the standard procedure how mathematical structures interact, the language types must follow the principle. There is no other way. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de