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From: =?iso-8859-15?Q?Yannick_Duch=EAne_=28Hibou57=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: Re: Lost in translation (with SPARK user rules)
Date: Thu, 27 May 2010 14:36:57 +0200
Organization: Ada At Home
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Date: 2010-05-27T14:36:57+02:00
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Le Thu, 27 May 2010 13:57:58 +0200, Phil Thornley  =

<phil.jpthornley@googlemail.com> a =E9crit:
> So my approach is now to create user rules so that the Simplfier
> proves 100% of the VCs.  However this sometimes requires quite complex=

> user rules that are difficult validate manually, so I use the Proof
> Checker to validate those rules by creating VCs that correspond to the=

> rule and proving those.
This is close to my personal wish too, except I see a slight difference =
:  =

I prefer to write very simple user rules, easily proved (like as easy to=
  =

prove as using a truth table) and write Check based demonstrations relyi=
ng  =

on these rules. This is because I feel it is more safe (enforce soundnes=
s)  =

and because it left more in the source in less in external documents (do=
es  =

not brake source navigability and layout logic).

-- =

There is even better than a pragma Assert: a SPARK --# check.
--# check C and WhoKnowWhat and YouKnowWho;
--# assert Ada;
--  i.e. forget about previous premises which leads to conclusion
--  and start with new conclusion as premise.