awesome-patterns/concurrency/fetch_urls/main.go

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
)

func main() {
	urls := []string{
		"http://www.reddit.com/r/aww.json",
		"http://www.reddit.com/r/funny.json",
		"http://www.reddit.com/r/programming.json",
	}

	resc, errc := make(chan string), make(chan error)

	for _, url := range urls {
		go func(url string) {
			body, err := fetch(url)
			if err != nil {
				errc <- err
				return
			}
			resc <- string(body)
		}(url)
	}

	for i := 0; i < len(urls); i++ {
		select {
		case res := <-resc:
			fmt.Println(res)
		case err := <-errc:
			fmt.Println(err)
		}
	}
}

func fetch(url string) (string, error) {
	res, err := http.Get(url)
	if err != nil {
		return "", err
	}
	body, err := ioutil.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		return "", err
	}
	return string(body), nil
}