From: "G.B." <bauhaus@futureapps.invalid>
Subject: Re: function Is_Open (File : File_Type) return Boolean; :Text_io
Date: Thu, 29 Oct 2015 12:47:48 +0100
Date: 2015-10-29T12:47:48+01:00 [thread overview]
Message-ID: <n0t0t1$56e$1@dont-email.me> (raw)
In-Reply-To: <190shqocxd87d$.1d68ghgqgbvfs$.dlg@40tude.net>
On 28.10.15 19:20, Dmitry A. Kazakov wrote:
>> >If the assumptions are correct, but the compiler cannot determine
>> >their truth, should we hide the assumptions?
> As hide from the compiler? Certainly so! If as you said the compiler has no
> idea what your assumption is supposed to mean, how can it generate a useful
> code?
You mean, contract code needs to add value to *executables*
other than run-time tests?
I think the biggest misunderstanding here is in asking for
contracts to be considered just expressions, and then analyzing
them like they were *meant* to be ordinary expressions.
Even so, I think that an implementation of Ada could "outsource"
assertion checking to some read-only copy of the program that
is running on a twin processor, suitably connected, so as to
reduce run-time effects of assertion checking.
> If you force it, it generates garbage, which the semantics of dynamic
> predicates is, a garbage.
No, the compiler will be effecting the computation of a result
that does not need to be computed because we know it is true.
However, we wish to say that we know what the compiler does not
know, because a conjecture is being used as an assumption
when designing our subprogram, say. If this assertion might
be checked at run-time due to some Assertion_Policy, then we
have to add a contraption,
Some_Assertion =>
Conjecture_X_To_Be_Assumed or else Conjecture_X (...);
So, if an algorithm is based on a conjecture, and we wish
to communicate what it is, precisely, a Boolean expression
allows us to do so. It documents our assumptions precisely.
next prev parent reply other threads:[~2015-10-29 11:47 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-26 10:00 function Is_Open (File : File_Type) return Boolean; :Text_io comicfanzine
2015-10-26 11:27 ` Simon Wright
2015-10-26 13:25 ` comicfanzine
2015-10-26 18:01 ` Simon Wright
2015-10-26 19:03 ` AdaMagica
2015-10-27 11:30 ` Simon Wright
2015-10-26 18:02 ` Jeffrey R. Carter
2015-10-26 13:28 ` comicfanzine
2015-10-26 15:07 ` Jacob Sparre Andersen
2015-10-26 16:37 ` AdaMagica
2015-10-26 20:46 ` J-P. Rosen
2015-10-27 8:42 ` comicfanzine
2015-10-27 11:34 ` Simon Wright
2015-10-28 13:32 ` comicfanzine
2015-10-27 8:51 ` comicfanzine
2015-10-27 17:15 ` Jeffrey R. Carter
2015-10-26 22:48 ` Bob Duff
2015-10-27 8:30 ` Dmitry A. Kazakov
2015-10-27 13:30 ` Bob Duff
2015-10-27 14:00 ` G.B.
2015-10-27 15:26 ` Dmitry A. Kazakov
2015-10-27 16:43 ` G.B.
2015-10-27 20:04 ` Dmitry A. Kazakov
2015-10-28 11:06 ` Georg Bauhaus
2015-10-28 17:58 ` Randy Brukardt
2015-10-28 18:20 ` Dmitry A. Kazakov
2015-10-28 20:36 ` Bob Duff
2015-10-28 21:02 ` Dmitry A. Kazakov
2015-10-29 11:25 ` AdaMagica
2015-10-29 13:37 ` Dmitry A. Kazakov
2015-10-29 17:57 ` AdaMagica
2015-10-29 18:12 ` AdaMagica
2015-10-29 18:26 ` Dmitry A. Kazakov
2015-10-30 8:27 ` Jacob Sparre Andersen
2015-10-30 9:11 ` J-P. Rosen
2015-10-29 11:47 ` G.B. [this message]
2015-10-29 13:01 ` J-P. Rosen
2015-10-29 14:00 ` Dmitry A. Kazakov
2015-10-30 1:06 ` Georg Bauhaus
2015-10-30 8:39 ` Dmitry A. Kazakov
2015-10-30 14:32 ` G.B.
2015-10-30 16:20 ` Dmitry A. Kazakov
2015-10-30 19:07 ` G.B.
2015-10-31 9:31 ` Dmitry A. Kazakov
2015-10-31 11:17 ` Georg Bauhaus
2015-10-30 14:40 ` G.B.
2015-10-30 16:26 ` Dmitry A. Kazakov
2015-10-28 20:07 ` Bob Duff
2015-10-28 20:59 ` Dmitry A. Kazakov
2015-10-27 14:02 ` G.B.
2015-10-27 15:10 ` Dmitry A. Kazakov
2015-10-27 16:41 ` G.B.
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