title: Print Positive and Negative Ints With Same Width in Fable
body: <p>I would like formatted integer strings with</p>
  
  <ul>
  <li>the sign (+/-)</li>
  <li>a width I specify</li>
  </ul>
  
  <p>In .NET,</p>
  
  <pre><code>sprintf "%+04i" 1
  sprintf "%+04i" -1
  </code></pre>
  
  <p>yields</p>
  
  <pre><code>+001
  -001
  </code></pre>
  
  <p>but in Fable</p>
  
  <pre><code>+001
  00-1
  </code></pre>
  
  <p>How do I get the .NET behavior?</p>