As I understand them, this isn't quite what I'm after. These are Lisps implemented in Python (at least Hy is -- I'm not familiar with Pymacs). I'm not fixated o

As I understand them, this isn't quite what I'm after. These are Lisps implemented in Python (at least Hy is -- I'm not familiar with Pymacs). I'm not fixated on Lisp, and just implementing an L1 (L1=Lisp for the sake of the example) interpreter on L2 doesn't seem to be what I'm after. I want to be able to use whatever language (L1) I like (within reason), and be able to call out to packages that happen to be written in whatever language (L2) the package authors preferred. Obviously you need to have the L2 runtime available, which is presumably how CLR (and JVM in the hypothetical above) sort of do this -- everyone runs on a common runtime, sort of like everyone use to compile to the metal so that (modulo struct wrangling) it didn't matter what L2 was bcs at the end of the day everyone talked machine language. The stupid obvious way to do this is, of course, just RPC where you call out to a python (or whatever) server, and this is what I actually do now, but the overhead of communications is ugly if not slow, and there's all sorts of issues with debugging etc.