You can search for identifiers within the package.
in-package search v0.2.0
val some_exn : 'a Js_of_ocaml.Js.Optdef.t -> 'a
module type Params = sig ... end
module Impl (P : Params) : Graphv_font.FontBackend.S with type Buffer.t = Graphv_webgl_impl.Buffer.UByte.t