title: How to use phase control of inlining in haskell?
body: <p>Documentation <a href="http://www.haskell.org/ghc/docs/latest/html/users_guide/pragmas.html#phase-control">says</a>, </p>
  
  <blockquote>
    <p>Sometimes you want to control exactly when in GHC's pipeline the INLINE pragma is switched on.</p>
  </blockquote>
  
  <p>Why should I ever want this? (Except when I also use RULES pragma, in this case I may want to postpone inlining of the function in order to let associated rules to be fired.) What kinds of functions are better to inline only at a particular stage of simplifying process?</p>