title: Convert integer list to a string
body: <p>I am trying to achieve the following. Input is list [8;9;4;5;7] and output should be 
  "8,9,4,5,7,"  Note the "," in the output</p>
  
  <p>I tried the following</p>
  
  <pre><code>let rec ConvertToString list =
     match list with
     | head :: tail -&gt; head.ToString() + ConvertToString tail
     | [] -&gt; ""
  
  let op= [8;9;4;5;7] |&gt; ConvertToString
  </code></pre>
  
  <p>But the output which i get is val me : string = "89457"</p>
  
  <p>Can anyone kindly suggest how to get get the "," in the output. The function should be generic.</p>