Lisp take on generating an embedded VM at runtime/ad hoc basis (vs. polymorphic coding)?

How would use the most recent 'trie of lisp git diffs' differ from command to do a system call fork of lisp / duplicate lisp lists / apply 'diffs' to forked system call of lisp?

Perhaps, lisp concurrency support without a system()/debugger.[1]

(humor) To bad iLisp would be confused with other brand name(s).

[1] : Evil Scheduler: Mastering Concurrency Through Interactive Debugging : http://aoli.al/blogs/deadlock-empire/