title: Golang reflect, how to get map value type?
body: <p>For a map <code>m</code> in golang, we can get simply the key type using <code>t.Key()</code>.</p>
  
  <p>But I wonder how to get the map value type? </p>
  
  <p>When the map is empty, we can not even use <code>v.MapIndex</code>, any idea?</p>
  
  <pre><code>m := map[string]int{}
  t := reflect.TypeOf(m)
  v := reflect.ValueOf(m)
  t.Key()
  v.MapIndex()
  </code></pre>