Blinking

blink.lua

local swap = function(a, b, last)
	return (last == b) and a or b
end

local period = 0.05
local blinkTimer
blinkTimer = function(len)
	timer.add(period, function()
		self.alpha = swap(0, 255, self.alpha)
		if len > 0 then blinkTimer(len-period) else self.alpha = 255 end
	end)
end
blinkTimer(0.2)

using love2d + hump