title: Correct terminology for continuations
body: <p>I've been poking around <em>continuations</em> recently, and I got confused about the correct terminology. <a href="http://www.haskellforall.com/2012/12/the-continuation-monad.html" rel="noreferrer">Here</a> Gabriel Gonzalez says:</p>
  
  <blockquote>
    <p>A Haskell continuation has the following type: </p>
  
  <pre><code>newtype Cont r a = Cont { runCont :: (a -&gt; r) -&gt; r }
  </code></pre>
  </blockquote>
  
  <p>i.e. the whole <code>(a -&gt; r) -&gt; r</code> thing is the continuation (sans the wrapping)</p>
  
  <p>The <a href="http://en.wikipedia.org/wiki/Continuation" rel="noreferrer">wikipedia</a> article seems to support this idea by saying</p>
  
  <blockquote>
    <p>a continuation is an abstract representation of the control state 
    of a computer program.</p>
  </blockquote>
  
  <p>However, <a href="http://www.haskell.org/haskellwiki/MonadCont_under_the_hood" rel="noreferrer">here</a> the authors say that</p>
  
  <blockquote>
    <p>Continuations are functions that represent "the remaining computation to do." </p>
  </blockquote>
  
  <p>but that would only be the <code>(a-&gt;r)</code> part of the <code>Cont</code> type. And this is in line to what Eugene Ching says <a href="http://www.codejury.com/continuations-in-haskell/" rel="noreferrer">here</a>:</p>
  
  <blockquote>
    <p>a computation (a function) that requires a continuation function in order 
    to fully evaluate.</p>
    
    <p>We’re going to be seeing this kind of function a lot, hence, we’ll give it 
    a more intuitive name. Let’s call them waiting functions.</p>
  </blockquote>
  
  <p>I've seen another tutorial (Brian Beckman and Erik Meijer) where they call the whole thing (the waiting function) the <em>observable</em> and the function which is required for it to complete the <em>observer</em>.</p>
  
  <ul>
  <li>What is the the continuation, the <code>(a-&gt;r)-&gt;r</code> thingy or just the <code>(a-&gt;r)</code> thing (sans the wrapping)?</li>
  <li>Is the wording observable/observer about correct?</li>
  <li>Are the citations above really contradictory, is there a common truth?</li>
  </ul>