Re: New aggregates with Ada 2022.

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2022-06-25 05:13, Randy Brukardt wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
> news:t93mr6$pvm$1@gioia.aioe.org...
>> On 2022-06-24 03:24, Randy Brukardt wrote:

>>> You're thinking too small. Obviously, in a language without an syntactic
>>> array construct, every data structure would be some sort of record.
>>
>> They are fundamentally different. Record interface is static mapping:
>>
>>     identifier -> value
>>
>> 1D array interface is dynamic mapping:
>>
>>     ordered value -> value
>>
>> It not only has run-time semantics of (indexing). It is also ordering of
>> the index which implies enumeration, ranges, slices.
> 
> Dymanic means a function. And there is no reason to treat a few functions as
> special (again, at the user level).

No. Identifier is not a value, it is a static name. This allows us to 
have any statically chosen type on the right side of the mapping.

With a dynamic mapping we must have the same type for all outcomes, e.g. 
of the array element.

>> I don't buy the idea of run-time penalty for having abstract data types
>> and I don't see why built-in arrays cannot coexist with user-defined ones
>> without turning the language into LISP.
> 
> They add a huge amount of complication for very little gain.

We have different priorities here. I see arrays with slices as one of 
the most important language features. Especially considering formal 
verification and validation.

>> Furthermore, the age of  free CPU cycles came to an end. Soon we will have
>> return back to sanity.
> 
> I don't think programming abstractly and translating that into good code
> will ever be a bad idea. After all, that is the idea behind Ada. If you
> truly want to worry about the cost of compilation, then you have program in
> a very close to the metal language, even lower level than C. And current
> machines are way harder to generate code for than the Z-80 that we started
> out on (and even then, we generated pretty bad code with the very tiny
> compiler).

No, I worry about cost of execution. You want to simplify the compiler 
at the expense of the program complexity and efficiency of its code.

> I'd rather plan for a future where the compiler tool set does a lot of
> correctness checking for one's programs;

Yes and correctness checking requires proper and very refined 
abstractions you are ready to throw away. Here is a contradiction. In a 
language like Forth there is basically nothing to check.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de