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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Half Constrained Array Types and Slices
Date: 10 Mar 2006 12:33:46 -0500
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Date: 2006-03-10T12:33:46-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> There is, but for most of finite bounds a string range would contain an
> uncountable number of items. For example "A".."B". This range includes
> "AA", "AAA", etc. This might be is undesirable, however, it would be
> interesting to think about how to deal with bounded infinite ranges, like
> "A".."B".

Note quite infinite, since X'Last <= Natural'Last for all Strings X.
And I suppose the highest value of String is:

    (Positive => Character'Last)

This leads nowhere useful!  ;-)

If you want "arrays" indexed by strings, you really want sparse arrays
implemented as hash tables or some such.  I call those "mappings", not
"arrays".  See the Containers library of Ada 2005.

>... After all [universal] floating-point ranges are allowed in Ada,
> and they aren't finite...

And they're not allowed in 'for' loops, nor as array indices.
Which is a good thing.

- Bob