That's why I said "their own" JS-based implementation. And the point is that it goes out of its way to re-invent features already supported by ES6 just so they

That's why I said "their own" JS-based implementation. And the point is that it goes out of its way to re-invent features already supported by ES6 just so they look more like Ruby. Like using string interpolation instead of template strings, for example. It's not a language built on top of JS to improve upon JS, it's just as contrived as CoffeeScript (which unlike this one actually had a reason to exist in that it influenced the development of ES6 when a lot of features it implemented weren't yet part of JS). What is the benefit of learning this language? Who is this for? JS programmers? No, they could just use Babel to write something that will eventually become vanilla JS. Does it bring anything new to the table like ClojureScript or LiveScript does? No, it's basically CoffeeScript with ES6 scoping rules and JSX elements. So in the end all it adds is another barrier to entry for new developers joining your project/company with the only benefit being that it's "prettier". I'm not saying bad ideas aren't worth exploring -- they are, and if your bad idea happens to involve creating your own programming language, all the more power to you. But the only "good" reason to use this language is if you want your JS to look like Ruby. Just like Haml is for people who want their HTML to look like Ruby; and like Sass (not SCSS, I mean the original braceless syntax) is for people who want their CSS to look like Ruby.