feature(lsp): add metamodel parser

[rgrinberg]

In preparation for 3.17, we should be able to replace the typescript parser with a code generator that depends on this json file.

[ulugbekna]

Interesting

1. is the plan to go from vscode.d.ts -> metamodel.json -> Metamodel.t -> generated ocaml code?
2. I don't see code generation, will the ocaml code generation come in another PR?
3. how do you generate this metamodel.json?

Also, during my work on semantic highlighting I changed data (ref) from int list to int array because it's more efficient, especially when we compute diff between data from previous response and the currently computed data. I wonder whether this work is a good place to discuss when we should treat json array as a list and when as an array.

[rgrinberg]

is the plan to go from vscode.d.ts -> metamodel.json -> Metamodel.t -> generated ocaml code?

Yes it is.

I don't see code generation, will the ocaml code generation come in another PR?

We already have a code generator that goes from typescript to OCaml. The plan is to replace the typescript parser with reading Metamodel.t. Hopefully this will simplify the maintenance.

how do you generate this metamodel.json?

It is generated for us already thankfully. I just copied it from the lsp spec repo.

Also, during my work on semantic highlighting I changed data (ref) from int list to int array because it's more efficient, especially when we compute diff between data from previous response and the currently computed data. I wonder whether this work is a good place to discuss when we should treat json array as a list and when as an array.

Sometimes it's possible to write the converters for the types that we need manually ourselves. It's possible to tell the code generator to exclude certain things from being generated. Another option would be to hack the generator to special case the semantic tokens.

[ulugbekna]

I'd love to work on inlay hints when we upgrade to 3.17. I'd like to show types as inlay hints for symbols #685

[rgrinberg]

Okay, let me start pushing the remaining of what I have.