title: Different behavior of cabal repl for library vs. executable
body: <p>Using <code>cabal repl</code> seems to do nothing at all when used on library projects, but works fine for executable projects.  Is this expected behavior that I just don't understand?</p>
  
  <p>If I have a file containing simply</p>
  
  <pre><code>go = putStrLn "test"
  </code></pre>
  
  <p>and use <code>cabal init</code> with all the defaults (but choose "library" as the type), then running <code>cabal repl</code> just produces the some text about configuring and preprocessing the library and never enters a REPL environment.  The exact same steps, but with "executable" selected as the type, puts me right into GHCi as expected.</p>
  
  <p>The code works fine when loaded directly into GHCi.</p>