Re: array from static predicate on enumerated type

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 2021-03-18 3:30, Matt Borchers wrote:
> On Wednesday, March 17, 2021 at 3:41:16 PM UTC-4, Dmitry A. Kazakov wrote:
>> On 2021-03-17 19:44, Matt Borchers wrote:


   [about "sparse" enumeration subtypes defined by static predicates,
    and arrays indexed by such subtypes]


>>> Nevertheless, it still feels like an unfinished feature as it is now.
>> It is not unfinished. It is irreparably broken.
> 
> And this does not make for good advertising for Ada.


Matt, you should be aware that Dmitry has strong opinions about language 
and program design that are not shared by all Ada users and Ada proponents.

To be sure, Ada is showing some of its age. Updates of the Ada standards 
have made extensive additions to the language, while taking great pains 
to remain mostly upwards compatible, not only in syntax and semantics 
but also in wider usability goals such as remaining competitive for 
hard-real-time embedded systems and safety-critical systems where 
implementation overheads and implementation complexity must be held 
down. This inevitably means that new high-level features such as static 
predicates cannot always be fully orthogonal to other features of the 
language.

There have been suggestions and discussion here of an "Ada successor" 
language, and Dmitry in particular thinks that the type system should be 
completely overhauled for such a new language. Unfortunately there seems 
to be no demand from any large potential user group for such a language, 
or if there is demand, it is being satisfied mostly by new "grass-roots" 
languages such as Rust.

I have some hope that the swiftly growing scope and impact of malware 
and SW security breaches will prompt a major effort to develop computer 
systems, including programming languages, which are provably secure and 
incorruptible, and perhaps that will be an opportunity for an Ada 
successor language.