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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
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Newsgroups: comp.lang.ada
Subject: Re: SPARK
Date: Mon, 17 May 2010 02:59:32 +0200
Organization: Ada At Home
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Date: 2010-05-17T02:59:32+02:00
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Le Sun, 16 May 2010 20:13:27 +0200, Peter C. Chapin <pcc482719@gmail.com=
>  =

a =C3=A9crit:
> My understanding is that assert prevents the simplifier from using  =

> previous
> material as hypotheses in following verification conditions---as you  =

> noticed
> in your experiments. John Barnes talks about this in his book a little=
.
> Mostly I think assert is intended for use in loops. Without it, SPARK =
 =

> needs
> to consider each loop iteration as a spearate path
Here is the word, as you said, this cut the path. That's what I've learn=
ed  =

later too. This starts a new path, with a new hypotheses set, and indeed=
,  =

forget about all previous.

Now we know why it is so.

> [...]
> So to summarize perhaps a good rule might be to use assert to express =
 =

> loop
> invariants and check for everything else. I welcome other comments on =
 =

> this.
It seems all is there.

> I'm learning as well.
Great! Cheers


-- =

There is even better than a pragma Assert: a SPARK --# check.

Wanted: if you know about some though in the area of comparisons between=
  =

SPARK and VDM, please, let me know. Will enjoy to talk with you about it=
.