Super new to Ocaml. How do I access the "nth" value of a list without using the List module?

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2

OCaml “lists” are inductively defined linked lists. A list is either empty ([]) or an element followed by a list (elem::list).

You can think of the linked list definition as

type 'a list =
  | []
  | (::) of 'a * 'a list

To process a list, you have to use pattern matching and usually recursion as well:

match list with
| [] -> (* handle empty case *)
| x::xs -> (* handle non-empty case *)

Here, x is a newly defined variable bound to the element and xs is a new variable set to the “tail” of the list.

You cannot have O(1) indexing of linked lists. You must linearly traverse them. However, OCaml does have arrays, which are fixed-size containers with O(1) indexing. Arrays are written [|1; 2; 3|] and accessed with array.(index).

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