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Date: Sat, 11 Mar 2006 10:38:52 +0200
From: Niklas Holsti <nobody@nowhere.fi>
Organization: Tidorum Ltd
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Subject: Re: Half Constrained Array Types and Slices
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Date: 2006-03-11T10:38:52+02:00
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Jeffrey R. Carter wrote:
> Randy Brukardt wrote:
> 
>> ... Empty arrays are never very useful, ...
> 
> FWIW, my opinions are closer to Brukardt's than to Duff's. However, null 
> arrays are often useful; there are whole classes of recursive algorithms 
> that look like
> 
> return G (X (X'First) ) & F (X (Index'Succ (X'First) .. X'Last) );
> 
> with a null array terminating the recursion.

I second Jeffrey's opinion. I find that empty arrays are very
useful for my applications (program analysis). I could live
with a language where A'First and A'Last are available only when
A'Length > 0 and might raise Constraint_Error if A'Length = 0.
However, "for I in A'Range loop .. end loop" should work even
when A'Length = 0 (and do nothing in that case).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .