Expressing physical units (Was: Reprise: 'in out' parameters for functions)

[Jacob Sparre Andersen <sparre@nbi.dk>]

Wojtek Narczynski wrote:

> Several warts. For example, [...] type system unable to express
> physical units, [...].

The type system is not _unable_ to express physical units.  It just
has some limitations in how you can do it.  And although I am annoyed
by the limitations, I still haven't seen a description of how the
language can make it easier, without introducing problems outweighing
the benefits [1].

> But the problem real problem IMO is that the development of the
> language has stagnated.

What to one programmer appears as stagnation, appears as stability to
another programmer.  IMO change is grossly overrated.

It is fine to use GNAT to do experiments with possible changes to Ada.
And it is also fine to merge the experiments with sensible results
into the standard, but I don't want to have to reread the LRM every
six month.

In general, change means cost (learning and tools).  If the cost isn't
exceeded by the benefits, then the change is bad.

Jacob

[1] I have tried to formulate such a modification to Ada myself, but
    ended up with something that appeared to be (provably) impossible
    to compile.
-- 
"Computer Science is to Science, as Plumbing is to Hydrodynamics"