Re: ADA Popularity Discussion Request

[Ludovic Brenta <ludovic.brenta@insalien.org>]

 (Keith H Duggar) writes:
> "Ada was an experiment that failed. It was specified in such a way
> that it's hard to get adequate performance. So a critical mass of
> users and vendors never materialized. Now we see people devoting
> more energy to making C/C++ safer for programming large systems."

I wouldn't consider whoever said that a guru.  A real guru keeps
posted about new developments.

> Can any of you help me understand the details behind what he stated?
> Was it difficult to write compilers that gave good performance? Was
> the language specification too complex or difficult to implement?

Most of this has to deal with history.

C was designed for ease of implementation; Ada was designed for
safety, predictability, portability and maintainability.  Of course,
Ada compilers are more difficult to write than C compilers.  This is a
Good Thing; it means that Ada compilers do more work for you than do C
compilers.  C++ compilers are quite hard to get right; but then again,
so are C++ programs.

In the early 1980's, the DoD mandated use of Ada for most new software
development.  Contractors used to provide expensive, proprietary, and
slow compilers just because the DoD mandated it.  In return, their
compilers were Validated, i.e. certified to conform to the Ada 83
standard.  There were a few vendors that did not actually believe in
Ada and offered only "check-box compilers" - compilers barely good
enough to check a box saying "yes, we support Ada" in a form, but
lacking any real features or tools for serious development.

But things have changed since then.  The "check-box" vendors have all
but disappeared; the remaining Ada vendors are all quite serious about
Ada and software quality.  The Ada language evolved into a powerful
object-oriented language (Ada 95) without losing any of its inherent
safety, and a new standard (Ada 2005) is in the works for even more
improvements.  There are several good, inexpensive Ada compilers to
choose from.  One such compiler is even free, both in the sense of
freedom and free beer.

> Or are there simply missing features that preclude some efficient
> coding idioms (does Ada have pointers?). I'm very ignorant when it
> comes to Ada so please forgive these newbie questions.

Yes, Ada does have pointers.  They're called "access types" in Ada.
In Ada 95, "access to subprograms" were added among other things.  The
"guru" you mentioned ought to know that.  The only feature that I
think Ada lacks is functional programming; apart from that, it has
everything C++ has, and more (don't talk to me about multiple
inheritance before you've read Tucker Taft's paper on the subject).

I think that Ada is still entrenched, and thrives in safety-critical
environments, but these environments are traditionally neither Free
Software nor commercial-off-the-shelf.  As a result, the millions of
lines of Ada programs out there that fly aircraft, run trains, or
control nuclear power stations remain largely unknown to the general
public.  I think that Ada deserves more exposure by means of more Free
Software and more COTS software.  There *are* quite a few available
free software packages out there, but not nearly as many as in other
languages.  Quality compensates for that, IMHO, but there is still the
nagging impression that Ada is being ignored by the masses.

I appreciate that you took the time to ask questions here rather than
just take some uninformed bloke's word for it.  I have found that the
people interested in Ada tend to be independent thinkers.  A scarcity
nowadays.

-- 
Ludovic Brenta.