Only nil and false evaluate to false. Because there's no distinction between nil and non-existent elements, checking the existence of an element with a value of

Only nil and false evaluate to false. Because there's no distinction between nil and non-existent elements, checking the existence of an element with a value of 0 requires that 0 evaluates to true, so you get this situation: while 0 do print("loops forever") end while not 0 do print("does nothing") end