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From: Richard Riehle <richard@adaworks.com>
Newsgroups: comp.lang.ada
Subject: Re: Anybody in US using ADA ? One silly idea..
Date: Thu, 16 Jan 2003 20:03:55 -0800
Organization: AdaWorks Software Engineering
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Xref: archiver1.google.com comp.lang.ada:33113
Date: 2003-01-17T03:54:43+00:00
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"Dmitry A. Kazakov" wrote:

> They are not, up to some limit. But the problem is whether the language
> gives you an opportunity to define new numeric types without the
> restrictions you do not need and close enough to the theoretical
> performance limit for the remaining restrictions. Ada almost can this.
> [Almost, because one cannot make a private type "numeric" for the
> compiler.]

In fact, I have a generic package, for creating generic formal package
parameters that looks like this:

         generic
             type Item is private;
             with function "+" (L, R : Item) return Item is <>;
             with function "-" (L, R : Item) return Item is <>;
             with function "*" (L, R : Item) return Item is <>;
             with function "/" (L, R : Item) return Item is <>;
             with function "=" (L, R : Item) return Boolean is <>;
             with function "<" (L, R : Item) return Boolean is <>;
             with function ">" (L, R : Item) return Boolean is <>;
             with function "<=" (L, R : Item) return Boolean is <>;
             with function ">=" (L, R : Item) return Boolean is <>;
             with function Zero_Equivalent return Item;
             -- with some additional generic formal subprogram parameters
       package Generic_Operators is end Generic_Operators;

This can be used in some other package as a generic formal package
parameter.

      generic
          with package Operators is new Generic_Operators<>;
      package Generic_Statistics is

          -- Any data type here

     end Generic_Statistics;

I published an article with the details for this in an old issue of
Ada Letters.

Richard Riehle