Re: SI Units Checked and Unchecked

["Dan'l Miller" <optikos@verizon.net>]

On Friday, August 10, 2018 at 9:50:53 AM UTC-5, Dmitry A. Kazakov wrote:
> On 2018-08-10 15:59, Dan'l Miller wrote:
> > On Friday, August 10, 2018 at 1:45:47 AM UTC-5, Dmitry A. Kazakov wrote:
> >> On 2018-08-10 00:12, Dan'l Miller wrote:
> >>
> >>> Actually, I am talking about compile-time checks within Ada source code for a gauge as would be
> >>> utilized on the GUI control screen of a chemical plant or a nuclear reactor, not some toy string
> >>> processing app that is the analogue of GNU Units.
> >>
> >> As I explained this design is technically not viable.
> > 
> > in today's Ada.
> 
> … Either way, classes of dimensioned object built as subtypes 
> with the unit being a constraint or as related types with the unit being 
> the type tag, most designs will use subtype- or class-wide objects.
> 
> We need a type system capable of static checks when constraints or tags 
> are statically known, a way to convert "Unit_Error may be raised" into 
> hard type error.

Well, now there is something that we can agree on.

> Then we will have both static checks and zero run-time overhead in 
> static cases and fallback to dynamic checks in class-wide cases.

I take it …

> In any Ada.

… that you don't think that “Then we … class-wide cases” sentence is achievable at all in any derivative of Ada due to some fundamental flaw in Ada, and that a significantly not-Ada language is the only hope of achieving that sentence.  Why so?