This looks vaguely relevant so figured I'd ask the question here. I'm working on what can be pretty well reduced to an AST builder. I have nodes of certain typ

This looks vaguely relevant so figured I'd ask the question here. I'm working on what can be pretty well reduced to an AST builder. I have nodes of certain types which come with a set of relevant properties as well as the set of types that you're allowed to nest. I'm looking for a markup language to express these schemas so that I can generate the UI components (given parent node X, generate a widget with a form that can be used to submit legal children) and perform validation (given AST tree coming from the client, validate it server-side before persisting it) Currently using JSON schema but it's very verbose. Any ideas?