The monad laws guarantee that there's no difference between do_x(); do_y(); and do_x_and_y(); where the latter is defined as { do_x(); do_y() }. In fact, monads

The monad laws guarantee that there's no difference between do_x(); do_y(); and do_x_and_y(); where the latter is defined as { do_x(); do_y() }. In fact, monads would be pretty useless if that were not the case.