stéphane ducasse wrote:

> in Pier or Smallwiki lukas uses the debugger to step over smalltalk  
> snippet to ensure that we cannot
> write crazy expressions. So this would be nice to use that facility  
> and to produce a site that people can try and propose them some  
> exercises.

A good approach might be zo parse expressions using the 
RefactoringBrowser and run some kind of interpreter on these.
You'd have an even safer environment, and could provide very nice 
rendering of the current state and call stack.
I've built such an interpreter to execute rules in a VA runtime image, 
and it works pretty well.

Cheers,
Hans-Martin