gistfile1.go

package main

import "fmt"

func MergeChannels(a chan int, b chan int) chan int {
	// Merges two channels of sorted ints.

	output := make(chan int)

	go func() {
		defer close(output)
		nextA, hasA := <-a
		nextB, hasB := <-b

		for {
			if !(hasA || hasB) {
				break
			} else if hasA && (!hasB || nextA <= nextB) {
				output <- nextA
				nextA, hasA = <-a
			} else {
				output <- nextB
				nextB, hasB = <-b
			}
		}
	}()

	return output
}

func main() {
	a := make(chan int, 5) // ", 5" adds a buffer, otherwise I couldn't just
	b := make(chan int, 5) // shove in a bunch of values at once, as below.
	merged := MergeChannels(a, b)

	a <- 1
	a <- 2
	a <- 4
	a <- 5
	b <- 3
	b <- 4
	b <- 6

	close(a)
	close(b)

	for value := range merged {
		fmt.Print(value, " ")
	}
	fmt.Print("\n")
}