queueOperations.ml

let push elem {frontSize; front; rearSize; rear; rotation} =
  check {
    frontSize;
    front;
    rearSize = rearSize + 1;
    rear = elem :: rear;
    rotation;
  }
;;

let peek {frontSize; front; rearSize; rear; rotation} = match front with
  | [] -> raise Empty_queue
  | firstElem :: restFront -> firstElem
;;

let pop {frontSize; front; rearSize; rear; rotation} = match front with
  | [] -> raise Empty_queue
  | firstElem :: restFront ->
    let newState = invalidate rotation in
    check {
      frontSize = frontSize - 1;
      front = restFront;
      rearSize;
      rear;
      rotation = newState;
    }
;;