fibonacci.re

let next = (seq: list(int)) : int =>
  switch (seq) {
  | [] => 0
  | [0] => 1
  | [x, y, ..._] => x + y
  };

let fib = (n: int) : list(int) => {
  let rec fib' = (m: int, seq: list(int)) : list(int) =>
    switch (m) {
    | x when x == n => [next(seq), ...seq]
    | x => fib'(x + 1, [next(seq), ...seq])
    };
  fib'(0, []);
};

Js.log(fib(26) |> List.rev |> Array.of_list);