You can search for identifiers within the package.
in-package search v0.2.0
module type Intf = sig ... end
module Spec : sig ... end
module Unix : Intf with type 'a io := 'a
module Make_Lwt (Lwt : sig ... end) (Lwt_io : sig ... end) : Intf with type 'a io := 'a Lwt.t with type filepath := string
module type Intf_Eio = sig ... end
module Make_Eio (Eio : sig ... end) : Intf_Eio with type 'a io := 'a and type filepath := [ `Dir ] Eio.Path.t