lua協同プログラムによるパイプフィルタの実現

--     ，           
function receive(prod)--    ，     
	local status,value=coroutine.resume(prod)
	return value
end

function send(x)--       
	coroutine.yield(x)
end

function producer()--          
	return coroutine.create(function()
		while true do 
			local x=io.read()
			send(x)
		end
	end)
end

function filter(prod)--             
	return coroutine.create(function()
		for i=1,math.huge do
			local x=receive(prod)--       
			x=string.format("%5%s",i,x)
			send()
		end
	end)
end

function consumer(prod)
	while true do
		local x=receive(prod)--       
		io.write(x,"
")
	end
end

consumer(filter(producer()))