A simpler http midleware implementation

simpler.go

package main

import (
	"net/http"
	"time"
	"log"
)

func main() {
    var h http.Handler = http.HandlerFunc(Router)
    h = Timer(h)
    h = DontCache(h)
    http.ListenAndServe(":80", h)
}

// Middleware

func DontCache(next http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        res.Header().Set("Cache-Control", "max-age=0, no-cache, must-revalidate")
        next.ServeHTTP(res, req)
    })
}

func Timer(next http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        start := time.Now()
        next.ServeHTTP(res, req)
        log.Printf("%d %s", time.Since(start).Nanoseconds() / 1e3, req.URL.Path)
    })
}

// Router

var routes = map[string]func(http.ResponseWriter, *http.Request){
	"/":      IndexHandler,
	"/hello": HelloHandler,
	"/world": WorldHandler,
	"/panic": PanicHandler,
}
func Router(w http.ResponseWriter, r *http.Request) {
	if handle, ok := routes[r.URL.Path]; ok {
		handle(w, r)
	} else {
		http.Error(w, "Not Found : "+r.URL.Path, 404)
	}
}
func IndexHandler(w http.ResponseWriter, r *http.Request) {
	http.Error(w, "Hello, World!", 200)
}
func HelloHandler(w http.ResponseWriter, r *http.Request) {
	http.Error(w, "Hello", 200)
}
func WorldHandler(w http.ResponseWriter, r *http.Request) {
	http.Error(w, "World", 200)
}
func PanicHandler(w http.ResponseWriter, r *http.Request) {
	log.Panic("REM WAS RIGHT")
}