Add helper functions

* Path.Set.sexp_of_t
* Module.iter
* List.last

src/import.ml

@@ -78,6 +78,11 @@ module List = struct
       max acc (String.length (f x)))
 
   let longest l = longest_map l ~f:(fun x -> x)
+
+  let rec last = function
+    | [] -> None
+    | [x] -> Some x
+    | _::xs -> last xs
 end
 
 module Hashtbl = struct

src/module.ml

@@ -54,3 +54,7 @@ let cmti_file t ~dir =
   match t.intf with
   | None   -> Path.relative dir (t.obj_name ^ ".cmt")
   | Some _ -> Path.relative dir (t.obj_name ^ ".cmti")
+
+let iter t ~f =
+  f Ml_kind.Impl t.impl;
+  Option.iter t.intf ~f:(f Ml_kind.Intf)

src/module.mli

@@ -35,3 +35,5 @@ val odoc_file : t -> dir:Path.t -> Path.t
 
 (** Either the .cmti, or .cmt if the module has no interface *)
 val cmti_file : t -> dir:Path.t -> Path.t
+
+val iter : t -> f:(Ml_kind.t -> File.t -> unit) -> unit

src/path.ml

@@ -220,7 +220,10 @@ end
 type t = string
 let compare = String.compare
 
-module Set = String_set
+module Set = struct
+  include String_set
+  let sexp_of_t t = Sexp.To_sexp.(list string) (String_set.elements t)
+end
 module Map = String_map
 
 module Kind = struct

src/path.mli

@@ -39,7 +39,10 @@ val sexp_of_t : t Sexp.To_sexp.t
 val compare : t -> t -> int
 (** a directory is smaller than its descendants *)
 
-module Set : Set.S with type elt = t
+module Set : sig
+  include Set.S with type elt = t
+  val sexp_of_t : t Sexp.To_sexp.t
+end
 module Map : Map.S with type key = t
 
 val kind : t -> Kind.t