The little requirement that your project has to be multi-user may have merited mention in your OP.

And as to your associated new question -- writing your own language -- I don't see how an eviscerated Perl can still provide even the functionality you've described. So maybe a new language has potential; maybe you simply need to code up a better sandbox; or maybe you should reconsider the design, aiming for a Q&A thread relying on users' machines for the computations.