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Date: Wed, 23 Jun 2010 14:24:35 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: Inferring array index type from array object
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Date: 2010-06-23T14:24:36+02:00
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On 23.06.10 11:03, J-P. Rosen wrote:

>>> 2. Is it possible to declare the index variable without hardcoding the
>>> index type (that is, to infer it from the array object)?
>>
> There is no point in doing this, since the type of the array /is/
> hardcoded anyway. You could allow the same "simplification" as for
> loops, but as mentionned above, I prefer the other way round: always
> explicitely give the type name.

Is the required name somehow related to why the Ada.Container generics
do not re-export the formal types?


But anyway, without Dmitry's abstractions, a partial
solution should work along these lines, I think,

generic
   type Index_Type is (<>);
   type Component_Type is private;
package GA is

   type Array_Type is array (Index_Type range <>) of Component_Type;

   generic
      with function "+" (Left, Right: Component_Type)
                         return Component_Type is <>;
      Zero: in Component_Type;
   package Algorithms is

      function Sum (A: Array_Type) return Component_Type ;

   end Algorithms;

end GA;