title: Appending a directory to watch-sources in SBT settings
body: <p>I would like to add a directory to the watchedSources setting to trigger a build task whenever I save a file in that directory.</p>
  
  <pre><code>override def baseProject = play.Project(
    moduleName,
    moduleVersion,
    dependencies = libraries,
    path = file(location),
    settings = moduleSettings ++ Seq(
      watchSources &lt;++= baseDirectory map { dir =&gt;
        Seq(
          dir / "src/main/javascript"
        )
      }
    )
  )
  </code></pre>
  
  <p>I can't seem to get around the following error:</p>
  
  <pre><code>type mismatch;
  [error]  found   : sbt.Project.Initialize[ScalaObject with Equals]
  [error]  required: sbt.Project.Initialize[sbt.Task[?]]
  [error] Note: ScalaObject with Equals &gt;: sbt.Task[?], but trait Initialize is invariant in type T.
  [error] You may wish to define T as -T instead. (SLS 4.5)
  [error]     watchSources &lt;++= baseDirectory { f =&gt;
  [error]                                     ^
  [error] one error found
  [error] (compile:compile) Compilation failed
  Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore?
  </code></pre>
  
  <p>How do I append a sequence of files to the result of the watched sources task?</p>