title: Appending lists in lambda
body: <p>This works in F# Interactive: </p>
  
  <pre><code>let (list:(int * int) List) = []
  list @ [(40, 60)];;
  </code></pre>
  
  <p>This doesent work in my program:</p>
  
  <pre><code>let rMouseEvent = 
      form.MouseClick.Add(fun args -&gt; list @ [(args.X, args.Y)]))
  </code></pre>
  
  <p>Can someone explain why, and help me solve this?</p>
  
  <p>The error says:<br>
  This expression was expected to have type<br>
    unit<br>
  but here has type<br>
    'a list -> 'a list</p>