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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Copy vector in Ada
Date: Wed, 7 Nov 2012 14:09:47 +0100
Organization: cbb software GmbH
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Date: 2012-11-07T14:09:47+01:00
List-Id: <comp.lang.ada>

On Wed, 07 Nov 2012 13:03:08 +0100, Georg Bauhaus wrote:

> On 06.11.12 20:47, Yannick Duchêne (Hibou57) wrote:
>> Now, talking about proper naming of things, how would you explain to a
>> student, that sometime “type” must follow the substitution principle, and
>> sometime, it do exactly the opposite?
> 
> The challenge is to explain why the substitution principle is
> a valid commandment:

It is not.

Positive is a legitime subtype of Integer even though violates the LSP.

The valid proposition is that you should not substitute something
non-substitutable, but you cannot enforce that through types. Correctness
cannot be ensured through type checks.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de