Re: Question on Ada Expressive Power

[<adaworks@sbcglobal.net>]

"Gene" <gene.ressler@gmail.com> wrote in message
news:1137978607.032607.315500@g43g2000cwa.googlegroups.com...
>
>  Haiku is expressively powerful, but one doesn't use it for general
> purpose communication...
>
I wrote about this in an article for Crosstalk a few years ago.  Others
have discussed it, I think, but I don't have other references.

There is a difference between expressiveness and expressibility.  We can
typically express the solution to any programming problem in any programming
language.   Some languages are directly expressive of certain kinds of
problems.  Others can be splicktled into service for expressing those
same problems.

For a long time, COBOL was horrible at expressing mathematical
functions such as Square root, but we could laboriously write long
obscure routines of our own to do that function.   C++ has a handy
little compound assignment statement that is quite expressive, but we
can get the same effect, though with longer statements, using almost
any other language.  Perl is expressive of regular expressions, but we
have a regular expressions package in Ada that helps.

Expressiveness, in computer programming, is the ease with which a
given language allows us to map the problem space to the solution
space.  It has nothing to do with the number of lines of executable
code are created.   Expressibility means that, regardless of how
expressive a language might be, we can always find a way, albeit
a difficult way, to finally solve the problem.

As to the Haiku example, in software we are concerned with reducing
ambiguity through expressiveness.   In poetry (seem William Empson's
"Seven Types of Ambiguity") we place value on ambiguity.  In art, we
want to allow for variations of interpretation.   Such variations are not
so highly valued in engineering - including software engineering.

Richard Riehle