besides that, my last thing, for Jsr 223: each engine context looks like it should have its own history, and a context = bindings, so the history can go into the bindings. So I’ll layer the check/compile/eval to have bottom most without history, layer as it is known now would be subclass with history built-in, and JSR 223 would use the lower level and pass it in each time. same engine therefore can process different contexts