(bind-func world_init
(lambda (w density)
(let ((data (world_data w)))
(doloop (k (world_data_size w))
(pset! data k 0))
(doloop (i (world_height w))
(doloop (j (world_width w))
(cell_set_value w i j
(if (< (random) density) 1 0)))))))