Re: compiler benchmark comparisons (was: naval systems)

[Richard Riehle <richard@adaworks.com>]

Pascal Obry wrote:

> And this can be said for many points. In almost all discussions I have with
> co-workers about programing languages features, each time I show on advantage
> in Ada I got something like "but this is also possible with XYZ language" !

The first time I encountered this argument, circa 1969, we were a Fortran shop
with a new contract from the Navy for a specialized inventory control system.
I was assigned project leader, and I suggested we do the project in COBOL
instead of Fortran.    There was no end of grumbling from the Fortranners who,
every time I would identify a key benefit of COBOL for this project, would
exclaim, "I can do that in Fortran."

Nearly any problem that can be solved in one programming language can also
be solved in any other language.   That is, the solution for every programming
problem is ultimately expressible in every other language.     To defend one's
choice of programming language using this rationale simply overlooks the
more important question.    Is language K more expressive of the problem
to solution mapping than language P?

Expressiveness is a far more important criterion than expressibility.  In Ledgard's
little diagram of soution-space mapped to problem-space, we see this issue
in broad relief.

There are, of course, trade-offs.   One language may be more expressive than
another, but may have insufficient built-in safeguards;  or it may not have the
critical mass in usage (e.g. Erlang), or it may have some other drawback.  However,
to say, "I can do that in my favorite language too," simply fails to recognize
the deeper issues one must consider in selecting a programming language
for a given project.

Richard Riehle