I've created a GIT repo for this, with an explanation and a grammar for the "language": https://github.com/d-cook/Circuit

To me it sounds like old and smart guys talking about Smalltalk + its environment, lisp + emacs (or + Cursive) or a bit like C# and the Unity3d Editor. Oh and let me add React-live here 🙂 https://github.com/FormidableLabs/react-live

Oh, MPS and Smalltalk are definitely in the same (or similar) vein for my overall goals! The demo I'm looking to make is just to make a tangible point or analogy about artificial boundaries, but definitely doesn't offer a solution for fluidly dissolving that boundary at will (unless you count manually rewriting code and manually implementing extra UIs and parsers, etc., for a one-time use scenario, which is not exactly practical). Those tools probably offer the highest degree of fluidity currently available (shout out to Glamorous Toolkit, too!), but what they don't do is make the live code (or equivalent) for the tool itself present and editable in itself. It's hard to explain in few words what that gains, but I think it's key to making truly moldable software in every sense.

Really interesting! 🙂

I explained a bit if this in this other thread: https://futureofcoding.slack.com/archives/C5U3SEW6A/p1569829071119800?thread_ts=1569596004.115400&cid=C5U3SEW6A