(define-struct board (vec))

(define make-empty-board
  (lambda () (make-board (make-vector *board-size* (make-vector *board-size* 'n)))))

(define display-board
    (lambda (board)
      (let display-row ((i 0))
        (begin
          (if (< i *board-size*)
              (let display-col ((j 0))
                (begin
                  (if (< j *board-size*)
                      (display-mark (vector-ref (vector-ref board-vec i) j)))
                  (display-col (+ 1 j)))))
          (display-row (+ 1 i))))))