title: What to do if libraries require a different version of `base`?
body: <p>I'm trying to install packages which require a different version of base than the one I have installed (I have <code>4.6.0.0</code>, they require <code>&lt; 4.6</code>). How can I install these on my system?</p>
  
  <p>Edit: These packages actually require older packages in order to build, not just as a .cabal constraint.</p>