Interpreter in PL/1

Hey Guy's,


I am writing an interpreter in PL/1??? I can see you heads now looking
at the terminal: "PL/1???????".


Yep. PL/1. It's a challenge :) I am inventing the wheel.


I am writing an expression evaluator to process some number crunching
without having to recompile the whole program back again.
ex: Put 1+1 into the interpreter, and 2 comes out...


I am planning to put some flow control statements in it too.
I am not using any tools like LEX and YACC to make my grammar work. I am
writing the whole thing in pure PL/1 using recursive descent techniques.
In fact, I am writing PL/1 in PL/1.
Does anybody have some more examples of source coding in C, (PL/1??),
pascal or other non object oriented language of an implementation of an
interpreter with type checing and flow control?
I am fed up with searching through the web looking for an interpreter
that doesn't use parsing and lexing tables to do the job?


I am interpreting the source code at run time. I am very aware that this
is not the best thing to do, but I think that it is good enough for now.
Later I wil extend the interpreter by constructing a parsing tree for
processing the flow inside, before I execute any statement in the input.


Sorry for my bad English...


tanx,
Sven


sven@innet.be


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