title: F# Incomplete structured construct
body: <p>I recently started learning F# and today I got error that i can't get rid of. I have following code:</p>
  
  <pre><code>open System
  
  [&lt;EntryPoint&gt;]
  let main argv =
  
      type BinaryTree =
          | Node of int * BinaryTree * BinaryTree
          | Empty
  
      let rec printInOrder tree = 
          match tree with
          | Node (data, left, right)
              -&gt; printInOrder left
                 printfn "Node %d" data
                 printInOrder right
          | Empty
              -&gt; () 
  
      let binTree = 
           Node(2, 
              Node(1, Empty, Empty),
              Node(4, 
                  Node(3, Empty, Empty),
                  Node(5, Empty, Empty)
              )
      )
  
  printInOrder binTree
  0
  </code></pre>
  
  <p>With this code I'm getting following error: </p>
  
  <blockquote>
    <p>Incomplete structured construct at or before this point in binding</p>
  </blockquote>
  
  <p>Unfortunately I have no idea how to fix it. This is code example from book Programming F# 3.0. </p>
  
  <p>I would very much appreciate any kind of answer that could help me understand how to avoid these kind of mistakes in future.</p>