Re: Making sense of predicates

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

On 22.10.13 15:38, Dmitry A. Kazakov wrote:
> On Tue, 22 Oct 2013 14:53:04 +0200, Georg Bauhaus wrote:
>
>> On 22.10.13 10:19, Dmitry A. Kazakov wrote:
>>> If you try, as Ada designers keep on doing, to handle that at
>>>  the language level for each built-in type individually, you indeed
>>>  end up with something as horrific as accessibility rules are.
>>>  That does not work.

>>  From a vendors' point of view, adding fancy stuff works,
>> immediately. If industry does not complain, why would we?
>
> Don't really understand your point. BTW,

I meant that Ada 2012 has got new things by "adding fancy stuff"
here and there as opposed to by "redesigning the language".

The first approach, "adding fancy stuff", is an excellent
source of arguments and illusions, as it serves make-believe
on several accounts:

- you can state that it is substantially easier to handle source
  text written in "compatible" dialects than it is to handle source
  text written in two related, though slightly different languages.

- or, that a patched language protects your investments better than
  a cleaned-up language.

- or, you lift that backwards compatibility steam hammer and
   most project managers think all is well.

But that's all just a fake, see below.

Try finding consistency in Ada business regarding the languages.
This is from Ada videos:

(1) "Many customers happily continue using Ada 95 only."
(2) "Backwards compatibility is a hugely important thing."

If "many" customers means "most" customers, then what is the
fraction of Ada customers actually affected by a redesigned
Ada 202Z, more than by another collection of patches and
additions, if (1) is true?

If (2) is real, is there a technical reason that prevents
translating to Ada 95 source text?  I don't see how there
could be a reason if at the same time compilers handle both
old and new dialects of Ada. I mean, no technical reason.

(3) "They perform object code verification."

Then, to start with, why are they using a different compiler
at all? How does backwards compatibility at the source level
matter so much if what really matters is (3)? Is backwards
compatibility not just irrational FUD that's so perfect a tool
in the hands of every salesperson? If is more than irrational
FUD, to what extent is it rational?  Does this extent warrant
an ever growing complexity of a backwards compatible language?

At least GNAT showcases the inconsistency in this regard:
it does support Ada 95 and Ada 20XY nicely, yet we can read
that it will be catastrophic if Ada ever deviates from Ada 95
more than what had to be allowed. GNAT handles both languages.
But see, both _languages_!  If the Ada language were redesigned,
we'd still have just two languages, and closely related!

IINM, they are merging Ada and SPARK at AdaCore. This reminds me
of Windows NT 3.51 -> 4.0, merging the core OS and its GUI.
For technical reasons? No.

> P.S. I would also object the very idea of design by industry requests.
> Industry by necessity is conservative and unimaginative.

The craftspeople, the engineers do not seem that unimaginative
to me; they frequently want to handle the new (to them)
interesting stuff, and even build it. Some are really into
engineering new thing, wanting to do it right, technically.

Minimalist project management is a different story. But its
conservative and unimaginative traits will be gone as
soon as there is 1 industry acting as one to get the tools
they all want, for their money. Not N non-cooperative companies
that are so easily handled by the oligopoly...

> I am not sure about you, but I regard myself as a part of
>the industry.

So did the Daimler Group manager who said, publicly, that
their software department was not going buy that new offering by
software maker MS!
I am almost certain MS's salespoeple rolled every honeypot they
could find towards Stuttgart to silence the man! That was just
one man in industry.