title: I don't understand :t for fromIntegral
body: <p><a href="http://learnyouahaskell.com/types-and-typeclasses#typeclasses-101" rel="nofollow noreferrer">LYAH</a> describes <code>fromIntegral</code> as:</p>
  
  <blockquote>
    <p>From its type signature we see that it takes an integral number and turns it into a more general number. That's useful when you want integral and floating point types to work together nicely.</p>
  </blockquote>
  
  <p>I don't understand how this function works at all or why it is needed from playing around with the interpreter. </p>
  
  <pre><code>fromIntegral 4 + 3.2
  7.2
  4 + 3.2
  7.2 -- seems to work just fine?!
  fromIntegral 6
  6
  fromIntegral 6.2
  -- raises an error
  
  :t fromIntegral
  fromIntegral :: (Integral a, Num b) =&gt; a -&gt; b -- does this mean it takes 1 arg or 2?
  </code></pre>