Printer for (nested) Shapeless-HLists with proper brackets

Printer.scala

trait Printer[L <: HList] extends DepFn1[L] with Serializable { type Out = String }

object Printer extends Printer0 {
    def apply[L <: HList]( implicit printer: Printer[L] ): Printer[L] = printer

    implicit def hnilPrinter[C]: Printer[HNil] = new Printer[HNil] {
        override def apply( t: HNil ) = "HNil"
    }

    implicit def nestedHlistPrinter[H <: HList, T <: HList](
        implicit
        ph: Printer[H],
        pt: Printer[T]
    ): Printer[H :: T] = new Printer[H :: T] {
        override def apply( t: H :: T ): Out = s"(${ph( t.head )}) :: ${pt( t.tail )}"
    }
}

trait Printer0 {
    implicit def hconsPrinter[H, T <: HList](
        implicit
        p: Printer[T]
    ): Printer[H :: T] = new Printer[H :: T] {
        override def apply( t: H :: T ): Out = s"${t.head} :: ${p( t.tail )}"
    }
}

REPL

scala> import shapeless._
import shapeless._

scala> def print[H <: HList]( h: H )( implicit p: Printer[H] ) = p( h )
print: [H <: shapeless.HList](h: H)(implicit p: Printer[H])p.Out

scala> 1 :: 2 :: ( "foo" :: 3 :: ( "bar" :: HNil ) :: HNil ) :: HNil
res0: shapeless.::[Int,shapeless.::[Int,shapeless.::[shapeless.::[String,shapeless.::[Int,shapeless.::[shapeless.::[String,shapeless.HNil],shapeless.HNil]]],shapeless.HNil]]] = 1 :: 2 :: foo :: 3 :: bar :: HNil :: HNil :: HNil

scala> print( res0 )
res1: String = 1 :: 2 :: (foo :: 3 :: (bar :: HNil) :: HNil) :: HNil