Considering it's not just a grab-bag of TC39 proposals (e.g. removing braces), I suspect rejected TC39 proposals will just... linger. I agree a research langua

Considering it's not just a grab-bag of TC39 proposals (e.g. removing braces), I suspect rejected TC39 proposals will just... linger. I agree a research language feels potentially useful — and in fact that's what CoffeeScript's real legacy is (arrow functions, splats, destructuring assignments, and ES6 classes among others are direct ports of CoffeeScript syntax features, and many of the original JS class proposals that CoffeeScript-style classes replaced were quite bad) — but I'd be similarly leery of using this to ship much.