>Are there pain points or disadvantages to libraries like Babel that we could address via the core language instead? I think the main disadvantage is that comp

>Are there pain points or disadvantages to libraries like Babel that we could address via the core language instead? I think the main disadvantage is that compilers need to target something, and then JS engines need to be able to optimize that code even after it's transpiled. That's something that bringing these features into the language itself can help. Take a look at async/await for an example of this. For a fairly long time it was extremely slow to run async/await when it was compiled to es5, because the subtleties required some fancy work on the part of the compilers, even going so far as to include a small runtime to achieve it. Once it was supported by the JS engines themselves, it pretty quickly matched the speed of code full of `.then` with promises. It's obviously not impossible, but I'm guessing it's much harder. There's a reason why the x86 architecture is still getting new features and additions, and it's not just for the comfort of people writing raw assembly. Then you need to think about other tooling. Linters, compilers, static analyzers, minifiers, they all need a way to analyze the code you are writing. If that code is using features that aren't "standard" (or are on track to become standard maybe), then it would quickly get much messier than it already is. You aren't just talking about compiling now, but also a unified way of adding "plugins" to linters, compilers, static analysis tools, syntax highlighters, minifiers, and more. Because adding a "syntax plugin" is a non-starter if it means we can't minify our code or run our linter, and creating a new "syntax plugin" would be much harder if you also had to make plugins and changes to all of those things to even let it begin to become useful. Adding this stuff to the language is where it belongs, things like types on the other hand I firmly believe belong in "compile to JS" languages or dialects like TypeScript or Flow. That's a great abstraction level for that, simply because it doesn't change the output of the code (for the most part), it just enforces restrictions on it.