run_screen = function(screen_name)
	local contents = love.filesystem.read('screens/'..screen_name)
	if contents == nil then
		print("couldn't read screen "..screen_name)
		return
	end
	local f, error = loadstring(contents, screen_name)
	if f == nil then
		print(screen_name..': '..error)
		return
	end
	f()
end