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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Community Input for the Maintenance and Revision of the Ada
 Programming Language
Date: Wed, 6 Sep 2017 16:30:20 -0500
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Xref: news.eternal-september.org comp.lang.ada:47956
Date: 2017-09-06T16:30:20-05:00
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"Vincent DIEMUNSCH" <vincent.diemunsch@gmail.com> wrote in message 
news:7d014624-d143-4564-abfa-802534693644@googlegroups.com...
Le samedi 2 septembre 2017 19:08:48 UTC+2, Jeffrey R. Carter a écrit :

...
>> What would A(+Red) mean? Indices don't have to be numeric.
>
>But an array index needs to be isomorphic to an Integer. It's an array ! 
>Not
>a dictionnary, or a hash table.

Why? In Ada 2012, if A is a hashed map, A(Red) is exactly a reference into 
hash table. (Yes, this is formally a function call, but it points out the 
continum of mapping that goes from a basic array object, thru a user-defined 
indexed object, to a function call -- all forms of mapping.)

...
>> A(+I) is already defined for numeric I. This would not be backward 
>> compatible,
>> so it's very unlikely to happen.
>
>Sure, it is not fully backward compatible. But by the way, only the absence 
>of any
>evolution is 100% backward compatible, isn't it ?

Not really true, there is a lot that can be done with pure extensions 
(think, for instance, conditional expressions in Ada 2012 -- their addition 
has no effect on existing Ada 95 code).

There are plenty of uses of unary "+" in existing code, changing the meaning 
would silently break such code -- the worst kind of incompatibility. That we 
would do only for a critical issue (like composition of record "=", and that 
was very controversal, we made the incompatible change only because we 
couldn't find a sensible compatible change), surely not for something that 
would save a handful of keystrokes. (And remember that readability is an 
important goal in Ada, saving keystrokes is not a goal!)

                      Randy.