title: spray Collection ToResponseMarshallable
body: <p>I am trying to return a List from my complete directive in spray-routing.</p>
  
  <pre><code>complete {
    List("hello")
  }
  </code></pre>
  
  <p>However, I am getting an error -</p>
  
  <pre><code>Expression of type List[String] doesn't conform to expected type ToResponseMarshallable
  </code></pre>
  
  <p>I am getting the same error with Seq. I see that marshallers for List and Seq are not provided by default in spray-httpx <a href="http://spray.io/documentation/1.2.2/spray-httpx/marshalling/" rel="noreferrer">documentation</a>. However, spray-json provides marshalling support in its DefaultJsonProtocol. I have imported spray.httpx.SprayJsonSupport._ and spray.json.DefaultJsonProtocol._ in my code, but that too hasn't helped.</p>
  
  <p>Any idea how can I marshal a List/Seq using spray-json? Or will I have to write my own Marshaller?</p>
  
  <p>(My scala version is 2.11.4)</p>