Would recursive modules be difficult (if possible) to implement? about gen_js_api HOT 1 CLOSED

I think the workaround is rather general. You can always lift all the "opaque" type declarations to break recursion at the type level.

As for a direct support, it does not seem out of reach. The simplest thing to do would be to generate recursive module implementations with the provide signatures, but in your example, these signatures hide the _to_js/_of_js functions which are required in the implementation. One could either extend the internal signatures (on the generated recursive modules), or ask the user to write:

module rec Contact : sig
   type t
   val t_of_js: Ojs.t -> t
   val t_to_js: t -> Ojs.t
   val get_contact_groups: ...
end = ...

from gen_js_api.