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Date: Wed, 23 Apr 2008 15:34:06 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: Ada.Strings.Bounded
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Date: 2008-04-23T15:34:06+02:00
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christoph.grein@eurocopter.com schrieb:
>> procedure Ex is
>>     type E is (A, B, C);
>>     X: E;
>> begin
>>     X := E'pred(E'succ(C));
>> end Ex;
> 
> You can have this:
> 
>   type Enum is (A, B, C, D);
>   type Sub is new Enum range A .. C;
> 
>   Sub'Succ (Sub'Last) = D
>   Sub'Pred (Sub'Succ (Sub'Last)) = C
> 
> Sub'Base has range A .. D.

Yes, but extending the set of values only shifts the
(theoretical) problem of 'Succ by one inductive step.
Once we forget about the type of unrepresentable numbers
the problem ceases to exist, I think.