This is damn good

DefaultType.scala

//source: http://www.cakesolutions.net/teamblogs/default-type-parameters-with-implicits-in-scala
object Prac {

  trait DefaultsTo[Type, Default]
  object DefaultsTo {
    implicit def defaultDefaultsTo[T]: DefaultsTo[T, T] = null
    implicit def fallback[T, D]: DefaultsTo[T, D] = null
  }

  type Def[Default] = {
    type l[Type] = DefaultsTo[Type, Default]
  }

  type Document = String
  class Storage[DocType: Def[Document]#l](name: String){
    def t:DocType = ???
  }

  def main(args: Array[String]) {

    val settings = new Storage("settings") // inferred as Table[Document]
    val s:Document = settings.t

    trait User
    val users = new Storage[User]("users") // inferred as Table[User]
    val ss:User = users.t
  }

}