title: Haskell third argument of showFFloat
body: <p>I was looking into some way to suppress scientific notation(a struggle every programmer has to deal with at some point) and I found this question:</p>
  
  <p><a href="https://stackoverflow.com/questions/37006362/haskell-how-to-avoid-scientific-notation-in-decimal-output/37009015">Haskell - how to avoid scientific notation in decimal output</a></p>
  
  <p>Now, the first answer uses something like this:</p>
  
  <pre><code>showFullPrecision x = showFFloat Nothing x ""
  </code></pre>
  
  <p>This works but I cant figure out what the last argument is and I dont want to just use code blindly.</p>
  
  <p>The documentation for <code>showFFloat</code> says its signature is <code>showFFloat :: RealFloat a =&gt; Maybe Int -&gt; a -&gt; ShowS</code>. Taking in a <code>Maybe Int</code> and most likely a float, but what is up with the last argument(in our case an empty string)?</p>