I've also been working on a Scala Driver in stealth mode, I've been able to successfully send a subset of queries. Though my primary focus has been on making sure queries are typed correctly in Scala. As well as concurrently engineering a good interface from typed objects to JSON data, so that you don't end up with Map[String, Any] or Array[Any] all over the place. My current approach is adopting some of the ideas from Bryan O'Sullivan's excellent Aeson library in Haskell.