how to get a sub list from a list in ocaml

I'm looking at the List documentation. It seems the library does not provide a sublist function.

I'm trying to get list of elements from i to j. Now I have to write it as:

let rec sublist list i j =
  if i > j then
    []
  else
    (List.nth list i) :: (sublist list (i+1) j)

which is quite concise but I'm questioning the efficiency of List.nth, because if it's O(n), I would rather have to write it in a less concise way.

I'm wondering why didn't they provide List.sublist func, if List.nth is not O(1), because it's such a quite common operation..