gist 7 https://medium.com/@francesc/two-ways-of-merging-n-channels-in-go-43c0b57cd1de

main.go

func merge(cs ...<-chan int) <-chan int {
	out := make(chan int)

	var cases []reflect.SelectCase
	for _, c := range chans {
		cases = append(cases, reflect.SelectCase{
			Dir:  reflect.SelectRecv,
			Chan: reflect.ValueOf(c),
		})
	}

	go func() {
		for {
			i, v, ok := reflect.Select(cases)
			if !ok {
				if len(cases) <= 1 {
					break
				}
				cases = append(cases[:i], cases[i+1:]...)
				continue
			}
			out <- v.Interface().(*objectState)
		}
		close(out)
	}()
	
	return out
}