title: F# How to call let function correctly? Function call in [<EntryPoint>] isn't working
body: <p>I am new to F#. What I am trying to do is to call <code>test</code> more than once to print out <code>Hello World</code>. In this example, I want to call <code>test</code> three times. When I run the code it only prints to console once. Even without the <code>test</code> call, it runs. I have the following code:</p>
  
  <pre><code>open System
  
  let test =
      let mutable output = ""
      output &lt;- "Hello World"
  
      printfn "%s" output
  
  [&lt;EntryPoint&gt;]
  let main argv = 
      test
      test
      test
      ignore(Console.ReadKey())
      0 
  </code></pre>