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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: New aggregates with Ada 2022.
Date: Thu, 30 Jun 2022 00:00:34 -0500
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:t9gunm$97a$1@gioia.aioe.org...
> On 2022-06-29 06:07, Randy Brukardt wrote:
>> What you say here is precisely how they should work. But you would make 
>> the
>> cost of supporting that necessary on every array object, because one 
>> could
>> not know when an array is passed as a parameter what sort of 
>> representation
>> it has. So one has to use dispatching helper operations to implement all
>> assignments. And that's way more expensive than traditional array
>> implementation.
>
> It is already there because Ada 83 arrays have definite and indefinite 
> representations. Adding a user-defined representation on top is nothing.

Actually, it changes everything. Array descriptors are easy, indeed, for 
many years Janus/Ada represented all arrays the same (an indefinite 
representation with a small descriptor containing a pointer at a data area). 
Changing the representation of the underlying data is where the cost is.

                                         Randy.