is_sorted

(* Write a function is_sorted : string array -> bool which checks if the values of the input array are sorted in strictly increasing order, implying that its elements are unique (use String.compare). *)

let rec is_sorted (a: string array) : bool =
  let sub_array = Array.sub a 1 (Array.length a - 1) in
  if sub_array = [||]
  then true
  else if String.compare a.(0) sub_array.(0) > 0
  then
    false
  else
    is_sorted sub_array
;;