Looks like it might fix three big issues I had with Cue:
1. The only way to use it is to run their Go CLI app to convert the Cue into JSON and then load that. That sucks. I want native support. Jsonnet does this a lot better (https://jsonnet.org/ref/bindings.html), and PKL at least supports 4 languages. Cue only supports Go directly. Not good.
2. Cue has a super fancy type system, but as far as I could figure out there's no way to actually take advantage of this in an IDE, which is like 60% of the benefits of fancy type systems. In a Cue document you can't say "this is the schema". XML had that decades ago (and it has awesome IDE integration with Red Hat's XML extension for VSCode). Even JSON can sort of do it via `$schema`. The docs are a bit scant but it looks like this supports it too. The fact that Cue doesn't sucks.
3. Cue is pretty much only a fancy type system. It's a really elegant and nice type system, but that's it. It doesn't even have functions. So it isn't going to help with a lot of the things that Jsonnet and PKL help with.
This is not really in the same area as Cue. It's a way more direct competitor to Jsonnet and looks better, based on my brief skim.
My only concern with these sorts of things is that they're basically a whole new programming language, but without many of the features you'd want from a real programming language. It's in an uncanny valley.
Does look nice though.