title: acid-state example error
body: <p>I'm trying to start using <code>acid-state</code> for a project, but I'm running into trouble running the demos.</p>
  
  <p>Running <a href="http://mirror.seize.it/acid-state/examples/HelloWorld.hs" rel="nofollow"><code>HelloWorld.hs</code></a> from <a href="http://mirror.seize.it/acid-state/examples/" rel="nofollow">this example collection</a> on my 64-bit box gives me the errors</p>
  
  <pre><code>acid-state.hs:26:7:
      No instance for (MonadState
                         HelloWorldState (Update HelloWorldState))
        arising from a use of `put'
      Possible fix:
        add an instance declaration for
        (MonadState HelloWorldState (Update HelloWorldState))
      In the expression: put (HelloWorldState newValue)
      In an equation for `writeState':
          writeState newValue = put (HelloWorldState newValue)
  
  acid-state.hs:29:43:
      No instance for (MonadReader
                         HelloWorldState (Query HelloWorldState))
        arising from a use of `ask'
      Possible fix:
        add an instance declaration for
        (MonadReader HelloWorldState (Query HelloWorldState))
      In a stmt of a 'do' block: HelloWorldState string &lt;- ask
      In the expression:
        do { HelloWorldState string &lt;- ask;
             return string }
      In an equation for `queryState':
          queryState
            = do { HelloWorldState string &lt;- ask;
                   return string }
  </code></pre>
  
  <p>The same thing happens with <a href="http://mirror.seize.it/acid-state/examples/HelloWorldNoTH.hs" rel="nofollow"><code>HelloWorldNoTH.hs</code></a> as well. Neither error manifests on a 32-bit system. Any ideas what's going on here? Did I fail to install (or improperly install) some required component? </p>
  
  <p>I'm running "<code>The Glorious Glasgow Haskell Compilation System, version 7.4.1</code>" on 64-bit Debian Wheezy (installed via the <code>haskell-platform</code> package), with Cabal <code>0.14.0</code>. The machine itself is a 64-bit Core i3. The 32-bit machine (which ran the demo successfully) differs in no non-obvious way.</p>