Merge channels in Golang

merge.go

package main

import (
	"fmt"
)

// merge prints stuff from two channels.
//
// This example is a friendly reminder, that closed channel still produces events in loop.
// https://play.golang.org/p/6TwGnvyvhQC
func merge(one, two chan int) {
	oneClosed := false
	twoClosed := false
	for {
		select {
		case res, ok := <-one:
			if !ok {
				oneClosed = true
				fmt.Println("one closed")
				break
			}
			fmt.Println("old ", res)
		case res, ok := <-two:
			if !ok {
				twoClosed = true
				fmt.Println("two closed")
				break
			}
			fmt.Println("new ", res)
		}

		if oneClosed && twoClosed {
			fmt.Println("done")
			return
		}
	}
}

func main() {
	fmt.Println("Hello, playground")

	one := make(chan int, 10)
	one <- 1
	one <- 2
	one <- 3
	close(one)

	two := make(chan int, 10)
	two <- 1
	two <- 2
	two <- 3
	two <- 4
	two <- 5
	close(two)

	merge(one, two)
}