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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,39579ad87542da0e X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit X-Received: by 10.180.11.232 with SMTP id t8mr724908wib.3.1369279471720; Wed, 22 May 2013 20:24:31 -0700 (PDT) Path: fw11ni1138wic.0!nntp.google.com!feeder1.cambriumusenet.nl!82.197.223.108.MISMATCH!feeder2.cambriumusenet.nl!feed.tweaknews.nl!194.109.133.86.MISMATCH!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!border4.nntp.ams.giganews.com!border2.nntp.ams.giganews.com!nntp.giganews.com!news.panservice.it!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Seeking for papers about tagged types vs access to subprograms Date: Thu, 16 May 2013 00:08:38 +0200 Organization: cbb software GmbH Message-ID: <1mg9eepp12ood$.14lj7s8a7eygd$.dlg@40tude.net> References: <1bfhq7jo34xpi.p8n2vq6yjsea.dlg@40tude.net> <12gn9wvv1gwfk.10ikfju4rzmnj.dlg@40tude.net> <1oy5rmprgawqs.1jz36okze0xju$.dlg@40tude.net> <1q2ql1e4rcgko.diszzq1mhaq8$.dlg@40tude.net> <518dedd4$0$6581$9b4e6d93@newsspool3.arcor-online.net> <1um7tijeo609b$.1gtdijp0acfmn$.dlg@40tude.net> <1nkyb845dehcu.1sd90udwsrpdu.dlg@40tude.net> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: 15waz9CoS+eMakbyhTPyFQ.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Date: 2013-05-16T00:08:38+02:00 List-Id: On Wed, 15 May 2013 17:12:09 -0400, Peter C. Chapin wrote: > On Wed, 15 May 2013, Dmitry A. Kazakov wrote: > >>> A type is a pair of sets: a set of values and a set of operations defined >>> over those values (for example as functions taking items from the first >>> set as a parameter). Either set can be empty. In any case "value" is most >>> certainly a programming language term. >> >> type Employee is ...; >> >> How is employee a language term? > > Weren't we talking about "value" as a programming language term? You consider value being a language term. I objected, pointing out that value is the meaning of some program state, the meaning which is always outside the language and from the problem space. The only case when a value can be an Ada term is when the program is an Ada compiler. > I > understand that to mean "value" as something used by people when talking > about programming languages. Yes. > "Employees" is just a name in some program... > and specifically the name of a type. I don't follow what this has to do > with a discussion about values. The type Employee has values denoting employees of some business in some Ada program. >> task type Driver is ...; >> >> Show me an RM section which defines the values of this type. > > The values of a task type are the code fragments that implement the > task. Here I'm speaking in general terms, of course. So, X, Y : Driver; have same values? You seem to confuse value for its representation. The value of a task type is not even computable, or the value of clock. The representation of a task value might be a combination of some code, TCB, the state of system queues etc. >> And the simplest possible example why the language has nothing to do with >> values is this: >> >> type Some_Transcendental_Numbers is (e, Pi, Euler); >> >> What is the value of e? > > Some_Transcendental_Numbers is an enumeration type. One of it's values is > 'e'. There is no significance to 'e' other than that. At least at the > level of types. And what significance has Ada.Numerics' e : constant := 2.71828_18284_59045_23536_02874_71352_66249_77572_47093_69996; -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de