Ember's Glimmer Engine
I always have a problem with these kinds of frameworks. Every time I try to use one, and want to do something more in-depth for fancy than a lot of the functionality out-of-the-box, then I end up having to hunt down the way to extend X feature, and it often takes me more effort to do that then just writing in the root language would be.That is to say: The abstraction isn't as expressive as the root language, and when I need something more expressive, then it's more troublesome than writing than the root language.The rendering engine here does seem to perform admirably, and I have to congratulate them on that. Maybe I've just been burned a few too many times from this kind of language.