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From: =?iso-8859-15?Q?Yannick_Duch=EAne_=28Hibou57=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: Re: SPARK and testing.
Date: Sat, 29 May 2010 01:06:46 +0200
Organization: Ada At Home
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Date: 2010-05-29T01:06:46+02:00
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Le Fri, 28 May 2010 14:59:38 +0200, Peter C. Chapin <pcc482719@gmail.com=
>  =

a =E9crit:
> I can elaborate on this a little more. In my case the program I'm  =

> working on
> now needs to compute the minimum model of a collection of Datalog rule=
s
> (Datalog is a simple logic language that has been discussed as a possi=
ble
> database query language). I don't know how to express such a complex, =
 =

> high
> level characteristic as a SPARK '--#post' annotation.
>
> What I need to say is that the information in an array Model_Area (an =
 =

> array of
> tuples) is the minimum model implied by the Datalog rules in a differe=
nt
> array Storage_Area. It is well beyond my skills with SPARK to say such=
 a
> thing. I'm not saying that it is beyond SPARK's ability to express tha=
t
> relationship, but for me it is just easier to explore the matter with =
a  =

> test
> program.
I believe there is indeed some reification capabilities in SPARK. This i=
s  =

not just that easy. I don't believe it would be more easy anyway with  =

other methods like B or VDM.

As long as you can write in SPARK, some pre/post matching an abstract da=
ta  =

type property, you can do the same in SPARK. The matter is, how difficul=
t  =

it is. And when I see things about SPARK, it mostly talks about avoiding=
  =

runtime error, and not so much about proving an ADT has this and that  =

property. Which does not mean it is not possible.

-- =

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.