Let me clarify by what I mean with productivity: I'm developing a couple personal apps (ie. one user and one developer), and because of that, the most important "feature" for me is my ability to crank out code. Compatibility, maintainability (or to be specific, the usual concern with multiple developers and such), speed, scaling etc. be damned.In a sense, I'm looking for the front end equivalent of Arc/ Lisp for UI developing. What should I be looking at?