Remove dead code

Reviewed By: mbouaziz

Differential Revision: D8220874

fbshipit-source-id: 583cc35

infer/src/istd/IList.ml

@@ -162,6 +162,4 @@ let rec drop list index =
   match list with _ :: tl when index > 0 -> drop tl (index - 1) | _ -> list
 
 
-let mem_nth list index = drop list index |> List.is_empty |> not
-
 let opt_cons opt list = match opt with Some x -> x :: list | None -> list

infer/src/istd/IList.mli

@@ -39,8 +39,5 @@ val merge_dedup : 'a list -> 'a list -> compare:('a -> 'a -> int) -> 'a list
 val drop : 'a list -> int -> 'a list
 (** [drop l n] returns [l] without the first [n] elements, or the empty list if [n > length l]. *)
 
-val mem_nth : 'a list -> int -> bool
-(** [mem_nth l n] returns whether the list [l] contains a [n]th element. *)
-
 val opt_cons : 'a option -> 'a list -> 'a list
 (** [opt_cons None l] returns [l]. [opt_cons (Some x) l] returns [x :: l]*)