Hello Go

hello.go

package main

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

const listenAddr = "localhost:4000"

func main() {
  http.HandleFunc("/", handler)
  err := http.ListenAndServe(listenAddr, nil)
  if err != nil {
    log.Fatal(err)
  }
}

func handler(w http.ResponseWriter, r *http.Request){
  fmt.Fprint(w, "Hello, web")
}