[ ( x y -- address )
  cells malloc >r
  dup cells >r
  [ r> r> r> 2dup >r >r swap malloc swap i swap array.put >r ] iterate
r> r> nip
] is 2D-array

[ ( a b address -- value )
  array.get array.get
] is 2D-get-element

[ ( value a b address -- )
  array.get array.put
] is 2D-put-element