title: Get random numbers in F#
body: <p>I have the following function in F#:</p>
  
  <pre><code>let randomCh () = 
          let random = Random()
          alph.Chars (random.Next (alph.Length - 1));
  </code></pre>
  
  <p>This function returns same value each time. I had same problem in C#, and solution very simple: create just one Random object like this:</p>
  
  <pre><code>    var rnd = new Random();
  
      for (int i = 0; i &lt; 10; i++)
          Console.WriteLine(rnd.Next(10));
  </code></pre>
  
  <p>How can I reach same behaviour in F#: get each time random value?</p>