Filtering "None"'(s) out of an Hlist

hlist.scala

object Hlister extends App {

  import shapeless._
  case class A(value: Int)
  case class B(value: Int)
  case class C(value: Int)

  trait folderLP extends Poly2 {
    implicit def default[T, L <: HList] = at[T, L]((t,acc) => acc)
  }
  object folder extends folderLP {
    implicit def some[T, L <: HList] = at[Some[T], L]((t, acc) => t.get :: acc)
  }


  trait SomeExtractor extends Poly1 {
    implicit def default[T] = at[T]((t) => HNil)
  }
  object SomeExtractor extends SomeExtractor {
    implicit def some[T] = at[Some[T]]((t)=> t.get :: HNil)
  }
  val result = Some(C(15)) :: Some(B(55)) :: Some(A(195)) :: HNil
  val result2= Option(C(15)) :: Option(B(55)) :: Option(A(195)) :: HNil

  val filtered = result.foldRight[HList](HNil: HNil)(folder)
  val filtered2 = test.flatMap(SomeExtractor)


}