Re: Extend slices for n dimensional arrays for Ada 202X

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

On 2017-01-28 00:37, Randy Brukardt wrote:

> ... general slices really don't fit very well into any type model since they're
> a different shape (in general) than the originating array type.

It depends on the slice. When some dimensions are collapsed the result 
is a different but related type. When all dimensions are retained the 
type is same (or equivalent).

You consider a scenario where the array and its "full" slice have the 
same representation like in Ada 83. It would mean either keeping actual 
constraints in the object (bad) or else providing a universal mechanism 
of user-defined constraints passed along with the object. [Generic user 
constraints]

Another method is using a class-wide operation where both array and 
slice are expected. Slice would be a sibling type of different 
representation, both array and slice derived from the same abstract parent.

P.S. My vision of ideal Ada is when its type system would allow moving 
built-in arrays and records into the specification of the package 
Standard. [Tagged types should have had nothing to do with record types.]

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