History of Rexx
Rexx is a procedural programming language developed on March 20, 1979.Rexx
allows programs and algorithms to be written in a clear and structured
way.It also allows experts and casual users to make easy manipulation of
the kinds of symbolic objects that people normally deal with.Symbols such
as words and numbers. Rexx is capable of using commands to its host environment
and to call programs and functions written in other languages. It was also
designed to be independent of its supporting system software when such
commands are kept to a minimum.
Uses of Rexx
Rexx can be used as an "application glue" language.It was designed so
that the same language can effectively and efficiently be used for many
different applications. This allows elimination of the learning of several
other languages. It provides simple framework with powerful character and
arithmetical abilities. Simple programs with minimum overhead can be written
in Rexx, and so can robust large programs. Although Rexx's layout may look
somewhat similar to that of a BASIC program, and can be used for many of
the same programs in which BASIC is used note Rexx is not BASIC.
Why Rexx should be studied further
Rexx should be studied further because Rexx is different from most languages.
It is a free-format language. It is simple which makes it a good first
language for beginners, and for experienced programmers it offers powerful
functions. Rexx is a language that was also designed to be used as a macro
language by arbitrary application programs. The idea is that application
developers don't have to design their own macro languages and interpreters.
Instead they use REXX as the macro language and support the REXX programming
interface. If a REXX macro comes across an expression or function call
that it cannot resolve, it can ask the application to handle it instead.
The application only has to support the features that are specific to it,
freeing the developer from handling the time-consuming task of writing
a language interpreter. And if all applications use REXX as their macro
language, the user only has to learn one language instead of a dozen.
Interpreters of Rexx
Rexx is executed by interpreter most of the time. This allows rapid
program development. This advantage allows the language to be very suitable
for modeling applications and products. There are at least three
REXX interpreters available. Two are Unix based and well-supported
by it authors. The third is MS-DOS interpreter. Regina is Anders
Christensen's REXX interpreter for various versions of Unix and VMS. Regina
and REXX/imc are in source form, BREXX is only available as binary.
Free Interpreters
Regina
BREXX Interpreter
REXX/imc Interpreter
How I Feel About Rexx
Rexx is a language that is not for everyone. Just like any other language
Rexx has it ups and downs. It all depends on the user. For some Rexx is
a language very similar to C, C++, or even Java. Some feel that is just
another way for someone in the computer world or field to make a quick
buck. But to some it is a new road to travel on the "Information Superhighway".
Rexx has been expanded to many other forms. You have NetRexx, ObjectRexx,
and ARexx just to name a few. I have found that Rexx is an interesting
language because of its simplicity. We are all individuals and what works
for me may not work for you.
Sample Code
Here is a simple example:
a = 10
b = 20
call first
call second
call third
exit
first:
say "first -- a is" a "b is" b
return
second: procedure
say "second -- a is" a "b is" b
return
third: procedure expose a
say "third -- a is" a "b is" b b = 30
call first
return
After execution of the program:
first -- a is 10 b is 20
second -- a is A b is B
third -- a is 10 b is B
first -- a is 10 b is 30
