1let rec ack x y = match (x,y) with 2 | (0, _) -> y + 1 3 | (_ , 0) -> ack (x - 1) 1 4 | (_, _) -> ack (x - 1) (ack x (y - 1));; 5 6for it = 1 to 1000 do let _ = (ack 3 6) in () done