[racket] Implementing an equal? method for a class

Yesterday, Gregory Woodhouse wrote:
>     (define b(make-vector 9 (make-vector 9 0)))

BTW, this is wrong -- it builds a vector of 9 zeros, then uses that
same vector 9 times:

  -> (define x (make-vector 2 (make-vector 2 0)))
  -> x
  '#(#(0 0) #(0 0))
  -> (vector-set! (vector-ref x 0) 0 1)
  -> x
  '#(#(1 0) #(1 0))
  -> (print-graph #t)
  -> x
  '#(#0=#(1 0) #0#)

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!