Make progress on {read,write}_path

1 files changed, 4 insertions, 0 deletions

diff --git a/src/Identifiers.ml b/src/Identifiers.ml
index 51a22072..04c5427b 100644
--- a/src/Identifiers.ml
+++ b/src/Identifiers.ml
@@ -21,6 +21,8 @@ module type Id = sig
 
   val vector_of_list : 'a list -> 'a vector
 
+  val nth_opt : 'a vector -> id -> 'a option
+
   module Set : Set.S with type elt = id
 
   val set_to_string : Set.t -> string
@@ -59,6 +61,8 @@ module IdGen () : Id = struct
 
   let vector_of_list v = v
 
+  let nth_opt v id = List.nth_opt v id
+
   module Set = Set.Make (struct
     type t = id