playframework/Play20 — pull request #242 by julienrf (2012-04-19 13:52:16+00:00)
Title: Refactor Json serializers and deserializers

* Removes `Writes[List[T]]`, `Writes[Seq[T]]`, and other `Writes` instances for collections. `Writes[Traversable[T]]` is enough now that `Writes[-T]` is contravariant.
* Removes `Reads[List[T]]`, `Reads[Seq[T]]`, and other `Reads` specialized instances for collections, provides instead a generic instance using `CanBuildFrom`. Note that I needed to remove the covariance annotation on `Reads` otherwise implicit resolution was not successful (I still don’t understand why, and would like to make `Reads` covariant again, any suggestion?).