Lambda the Ultimate

Did you ever try to do that? Nesting functional into imperative code is easy, you just do the FP magic when you call the function. But how to do it the other way around?

Assume that you have a functional code as a base and some imperative code here and there, maybe even stored as strings in variables. Now you have to call something like Javascript "eval" when you want to run the imperative code. But when to do it? Note that imperative code doesn't have to be in a form of a function that returns some value. It can setup some event actions or mess around with some shareable memory states.

When to call such an imperative processes? I guess some event would apply, but what?

In fact I'm working on a functional language that can easily translate any abstract syntax tree (AST) into another AST. The language is interpreted inside javascript (maybe I'll try to do a native version in the future) and in a runtime of interpreting it I want to occasionally translate arbitrary imperative language AST into javascript AST (or assembler AST in the future) and execute it. The problem is how and when to trigger this execution. Maybe someone could help me with this problem?