title: How to add documentation after packages have already been installed?
body: <p>I have installed a bunch of packages to the snapshot database. I would now like a local copy of their documentation (even better if it's with <a href="https://www.reddit.com/r/haskell/comments/3ecest/haddock2161_released_with_source_code/" rel="nofollow">hyperlinked source</a>). Is there a way I can tell <code>stack</code> to run <code>haddock</code> on all of them?</p>
  
  <p>EDIT (copied from my answer):</p>
  
  <p>It seems that the obvious <code>stack haddock package</code> will install haddock for the package, so </p>
  
  <pre><code>$ cd ~/.stack/snapshots/x86_64-linux/lts-3.0/7.10.2/doc
  $ stack haddock *
  </code></pre>
  
  <p>seems to do what I want, with two downsides:</p>
  
  <ol>
  <li>I'll still need to remember to pass the <code>--haddock</code> flag to every <code>build</code> (there isn't a <code>~/.stack/config</code> file, is there?)</li>
  <li>It seems to rebuild them; is there a way to avoid that?</li>
  </ol>