title: Nested control structure in Haskell
body: <p>Is there any way to create nested control structure?
  For example I tried this. But I got error.</p>
  
  <pre><code>bmiTell :: (RealFloat a) =&gt; a -&gt; String  
  
  bmiTell bmi  = if bmi &lt;= 18.5  then if bmi==16.0 then "asdasdasdsad"
             else if bmi &lt;= 25.0 then "You're supposedly normal. Pffft, I bet  you're ugly!"  
             else if bmi &lt;= 30.0 then "You're fat! Lose some weight, fatty!"  
             else    "You're a whale, congratulations!"  
  </code></pre>