The feature that mrkeen is describing is called higher kinded types (HKT). I.e. in Scala (and similarly in Haskell), you could write something like: def pr

The feature that mrkeen is describing is called higher kinded types (HKT). I.e. in Scala (and similarly in Haskell), you could write something like: def process[L[_]](input: L[Int]): Unit = ??? Where `L[_]` could be any type that has a type parameter, e.g. `List[_]`, `Option[_]`, `Future[_]` or `Either[String, *]`. This opens the door to a new level of abstraction where other languages must resort to code generation or similar ad hoc-like solutions.