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,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,ab1d177a5a26577d X-Google-NewGroupId: yes X-Google-Attributes: gida07f3367d7,domainid0,public,usenet X-Google-Language: ENGLISH,UTF8 Received: by 10.68.8.135 with SMTP id r7mr10130021pba.8.1317780805529; Tue, 04 Oct 2011 19:13:25 -0700 (PDT) Path: lh7ni11785pbb.0!nntp.google.com!news1.google.com!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?= =?utf-8?Q?=29?= Newsgroups: comp.lang.ada Subject: Re: What's wrong with C++? Date: Wed, 05 Oct 2011 04:13:22 +0200 Organization: Ada @ Home Message-ID: References: <1ee1a434-4048-48f6-9f5e-d8126bebb808@r19g2000prm.googlegroups.com> NNTP-Posting-Host: a9sireMHQEFOj07CJcA02Q.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: Opera Mail/11.51 (Linux) X-Notice: Filtered by postfilter v. 0.8.2 Xref: news1.google.com comp.lang.ada:18303 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-Transfer-Encoding: Quoted-Printable Date: 2011-10-05T04:13:22+02:00 List-Id: Le Wed, 05 Oct 2011 03:53:28 +0200, Peter C. Chapin = a =C3=A9crit: > I don't think this is a big deal. It's an interesting theoretical > observation with little practical significance. Bad theoretical background is no good (at least, it matters to me, to me= , = it is a base of trustability). > Nobody is injured by the program > it didn't create; it's only an inconvenience to the programmer who has= to > adjust the source. Except the comment which follows the one I quoted, says > oops, the C++ spec allows implementations to terminate compilesif they= = > recurse too deeply. Nevermind. That's no good again. After that, a compiler, may produce invalid output= . > C++ isn't alone with this problem either. I understand that Scala's ty= pe > system is also Turing complete. Did not learned Scala yet (you recalled me to do it a future day, thanks= = for that) > It is possible, apparently, to write a > Scala program for which type checking never terminates. Again it's an > interesting theoretical observation but I don't think anyone really = > cares. Really, I do, this really frighten me. I could not trust such a language= . > In our work at VTC on translating some NASA software to SPARK we > encountered a situation where the SPARK simplifier took an "infinitely= " > long time to execute... well, okay, it only took about an hour. Yes it= > did terminate but it took so long that development was impractical (no= > different, really, than true non-termination). Our response: fix the > source. That's not the same. When a Prolog program does not terminates, this = means: =E2=80=9Cnothing proved=E2=80=9D, =E2=80=9Cdon't known=E2=80=9D, = =E2=80=9Cuninterpretable=E2=80=9D. If you stop it = after some time because you don't even know if it gonna ever terminates,= = that's the same, =E2=80=9Cuninterpretable=E2=80=9D. And for you, it did = terminates, it did = not stop after a too much deep recursion, then proudly asserting, =E2=80= =9COK = guys, that's fine, your VC is proved=E2=80=9D. Or did it ? -- = =E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [Ep= igrams on = Programming =E2=80=94 Alan J. =E2=80=94 P. Yale University] =E2=80=9CStructured Programming supports the law of the excluded muddle.= =E2=80=9D [Idem] Java: Write once, Never revisit