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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: {Pre,Post}conditions and side effects
Date: Fri, 8 May 2015 18:24:28 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2015-05-08T18:24:28-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:12gipcoheoucz.15ckvrgi11h3a.dlg@40tude.net...
> On Thu, 7 May 2015 14:01:34 -0500, Randy Brukardt wrote:
...
> It is an infinite recursion, which is why it is meaningless to define
> correctness, as you seem do, as some absolute. There cannot be such thing.

I totally agree; it doesn't make any sense to talk about a "correct 
program", or for that matter, a correct part of a program.

It can only be correct in a particular environment with particular code 
generated. The only tool that could possibly know enough of this is the 
compiler -- no other tool could come close.

...
> The point is that these are fundamentally different things. Correctness is
> outside. Behavior is inside.

The only thing that matters is behavior. I care about correctness of the 
behavior (which for Ada, mainly boils down to how and when exceptions are 
possible).

There is no such thing as a correct program (or part of a program) outside 
of its behavior. It's madness to even talk about it. Programming languages 
aren't defined well enough for the concept to be remotely meaningful.

                             Randy.