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!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Ada-Oriented GUI Date: Wed, 28 Mar 2018 17:02:49 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <9ed9edb1-3342-4644-89e8-9bcf404970ee@googlegroups.com> <26a1fe54-750c-45d7-9006-b6fecaa41176@googlegroups.com> <656fb1d7-48a4-40fd-bc80-10ba9c4ad0a4@googlegroups.com> NNTP-Posting-Host: MyFhHs417jM9AgzRpXn7yg.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 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 Content-Language: en-US X-Mozilla-News-Host: news://news.aioe.org X-Notice: Filtered by postfilter v. 0.8.3 Xref: reader02.eternal-september.org comp.lang.ada:51234 Date: 2018-03-28T17:02:49+02:00 List-Id: On 28/03/2018 16:09, Alejandro R. Mosteo wrote: > On 24/03/18 14:12, Dmitry A. Kazakov wrote: >> Now, programming this is like scratching your left ear with the right >> hand. I keep on asking for co-routines in Ada to break out of this >> lousy awful mess. To rein assorted mess of events/callbacks into a >> sequence imperative calls to be a able to program it as if it were an >> uninterrupted thread of control maintaining its state, just like if >> the I/O were synchronous. > > I've never used coroutines. Since this kind of "imperative-like" > sequences is what Rx provides, I understand that coroutines will allow > the same without staying in the declarative realm? I think so. Let you have Start_Write call and Write_Complete callback. The idea is to be able to write code in a "blocking" manner like: declare State : ...; -- Data local to the co-routine begin Start_Write (...); Wait_For_Complete (...); -- Give up the thread of control until ... -- Write_Complete Start_Write (...); ... My understanding is that the "functional" style with closures is an alternative to this which calls Start_Write and then queues a closure to be called on Write_Complete. The closure will carry State with it and perform chained actions. Needless to say that I don't find closures any appealing. > There are AIs for generators in Ada, maybe these will be among the > chosen ones? AFAIK, this is not what is required in order to support the above. A co-routine needs a local stack not bound to any task and a method to convert blocking calls into "save state, give up, wait for a callback/event". P.S. Maybe all this would become irrelevant for processors with thousands of cores. Then we would be able to run anything in a blocking manner without context switching penalty. I think that memory bottleneck would likely kill such architectures, but who knows... -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de