A HTTP version of Hello world in Go

hello.go

package main

import (
	"encoding/json"
	"flag"
	"github.com/bmizerany/pat"
	"io"
	"log"
	"net/http"
)

type Response struct {
	Hello string
}

func HelloWorld(w http.ResponseWriter, req *http.Request) {
	var response Response
	response.Hello = req.URL.Query().Get(":name")
	b, err := json.Marshal(response)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	io.WriteString(w, string(b))
}

func main() {
	var addr string
	flag.StringVar(&addr, "addr", "127.0.0.1:8000", "Bind to this address:port")
	flag.Parse()

	m := pat.New()
	m.Get("/hello/:name", http.HandlerFunc(HelloWorld))
	http.Handle("/", m)

	err := http.ListenAndServe(addr, nil)
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}