Golang chan-in

main.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	a := asChan(1, 2, 3, 4, 5)
	b := asChan(6, 7, 8, 9, 0)
	out := merge(a, b)
	for n := range out {
		fmt.Println(n)
	}
}

func merge(in ...<-chan int) <-chan int {
	out := make(chan int)
	var wg sync.WaitGroup
	wg.Add(len(in))
	for _, i := range in {
		go func(i <-chan int) {
			for n := range i {
				out <- n
			}
			wg.Done()
		}(i)
	}
	go func() {
		wg.Wait()
		time.Sleep(time.Second * 3)
		close(out)
	}()
	return out
}

func asChan(in ...int) <-chan int {
	out := make(chan int)
	go func() {
		for _, i := range in {
			out <- i
			// time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
		}
		close(out)
	}()
	return out
}