Re: ADA Popularity Discussion Request

[Marin David Condic <nobody@noplace.com>]

Keith H Duggar wrote:

> 
> If I may explain. I'm a proficient C++ coder and have been
> using it for scientific research coding for eight years. And
> I have experience with various other languages including C
> and Fortran.

I think you will find that Ada is a really wonderful language for 
scientific programming. It has excellent support for mathematical 
programming. (Look at the attributes for floating point numbers, for 
example.) The only area I could think of it being weak in that regard is 
perhaps having a plethora of mathematical libraries already in 
existence. They do exist, but probably not in the number they do in 
Fortran and to my disappointment, there are not a large number of math 
libraries (beyond log and trig stuff) that are either part of the 
standard or so ingrained that they might as well be part of the 
standard. Still, with all the numeric types, standard attributes and 
other features, if you want mathematical precision, Ada can give it to you.


> 
> "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."
> 
"Failed" may be a bit of a relative term. I don't think it achieved its 
stated goals, but it is still used in a variety of places for its 
inherent advantages. It is certainly not as big a language as I think it 
ought to be given its merits and the ammount of money thrown at it.

As for inherent inefficiency, this is largely a myth. Part of the 
problem was that 'Back In The Day..." Ada had a lot of new concepts that 
compiler writers didn't thoroughly understand. It also had lots of 
implied runtime checking going on that added overhead to executable 
code. The thing is that fundamentally, all of its structures *can* be 
implemented efficiently and these days, they typically are. Runtime 
checks *can* be turned off when you want efficiency and, for the small 
number of applications where it makes a difference, they typically are 
disabled.

So the efficiency thing kind of came about because of bad initial 
implementations and was fueled by people looking for excuses not to use 
the language. Now, this is not true, but its hard to overcome the bad 
reputation. If you want proof by demonstration, get the free Gnat 
compiler and do some benchmarking with it. Its also a C compiler. Write 
some example code typical of what you do and clock it. Chances are, *if* 
you learn to use the compiler effectively (setting the optimization 
switches, turning off checks, etc.) you'll find it is competitive with 
equivalent C code.



> 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?
> 

Back in 1983, Ada rather exceeded the capacity of existing computer 
hardware and strained the limits of compiler technology. Sooner or 
later, both caught up and these days, efficiency is hardly a concern.

> 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.
> 
Naturally, Ada has pointers. They are called "access types". Be aware 
that usually when a C/C++ programmer starts talking about pointers from 
an efficiency standpoint, they mean as a mechanism for passing 
parameters to subroutines. This is because C was developed at a really 
primitive level. Compilers are perfectly capable of deciding that a data 
structure is too big to pass on the stack and will generate a reference 
automagically for you. No need to fuss with dereferencing pointer 
parameters inside your subroutines, etc. Its all done behind the scenes. 
*Trust* the compiler in that regard and learn to use it effectively.

Ada programs typically use pointers a *lot* less than do C/C++ programs 
because they don't need them. However, when you want to build linked 
data structures or other things where pointers are needed, Ada has them. 
Just don't try to write C++ code in Ada syntax or you'll find it is 
really tough to do.

MDC


-- 
======================================================================
Marin David Condic
I work for: http://www.belcan.com/
My project is: http://www.jsf.mil/NSFrames.htm

Send Replies To: m   o   d   c @ a   m   o   g
                    c   n   i       c   .   r

     "All reformers, however strict their social conscience,
      live in houses just as big as they can pay for."

          --Logan Pearsall Smith
======================================================================