Cue also solves this problem. The "no" example is right on the front page: https://cuelang.org https://cuelang.org I used it for configuration of a Go program

Cue also solves this problem. The "no" example is right on the front page: https://cuelang.org https://cuelang.org I used it for configuration of a Go program recently and found it pleasant to work with. I hope the language is declared stable soon, because it's a good model.