simple chat example in go. uses channels to match partners and goroutines for concurency

chat.go

package main

import (
	"fmt"
	"io"
	"log"
	"net"
)

const listenAddr = "localhost:4000"

var partner = make(chan io.ReadWriteCloser)

func match(c io.ReadWriteCloser) {
	fmt.Fprint(c, "Waiting for a partner....")
	select {
	case partner <- c:
		// now handled by the other goroutine
	case p := <-partner:
		chat(p, c)
	}
}

func chat(a, b io.ReadWriteCloser) {
	fmt.Fprintln(a, "Found one! Say Hi!")
	fmt.Fprintln(b, "Found one! Say Hi!")
	go io.Copy(a, b)
	io.Copy(b, a)
}

func main() {
	l, err := net.Listen("tcp", listenAddr)
	if err != nil {
		log.Fatal(err)
	}

	for {
		c, err := l.Accept()
		if err != nil {
			log.Fatal(err)
		}
		go match(c)
	}
}