ConstZipper zips an HList with a constant value

ConstZipper.scala

import shapeless._

object cz {

	trait ConstZipper[L <: HList, C] extends DepFn2[L, C] { type Out <: HList }

	object ConstZipper {

		type Aux[L <: HList, C, Out0 <: HList] =
			ConstZipper[L, C] { type Out = Out0 }

		implicit def hnilConstZipper[C]: Aux[HNil, C, HNil] =
			new ConstZipper[HNil, C] {
				type Out = HNil
				def apply(l : HNil, c : C): Out = l
			}

		implicit def hlistConstZipper[H, T <: HList, C](implicit
			mct : ConstZipper[T, C]
		) = new ConstZipper[H :: T, C] {
			type Out = (H, C) :: mct.Out
			def apply(l : H :: T, c : C): Out = (l.head,c) :: mct(l.tail, c)
		}

	}

	def constZip[L <: HList, C, Out0 <: HList](l: L, c: C)(implicit
		icz : ConstZipper.Aux[L, C, Out0]
	): Out0 = icz(l, c)

}

import cz._

val l = 1 :: "a" :: true :: HNil
constZip(l, "const")

Thank you! That really looks easier to understand. And also explains the purpose of Aux classes.