GeneralShow.scala

import cats._
import cats.data._
import cats.implicits._
import shapeless._

object GeneralShow {
	implicit val hnilShow = Show.show[HNil](_ => "")

	implicit def hconsShow[H, T <: HList](
		implicit
		hShow: Show[H],
		tShow: Show[T]
	): Show[H :: T] = new Show[H :: T] {
		def show(ls: H :: T): String = ls.head.show + " " + ls.tail.show
	}

	implicit def autoShow[T, Repr](
		implicit
		genericT: Generic.Aux[T, Repr],
		genericShow: Lazy[Show[Repr]]
	): Show[T] = new Show[T] {
		def show(t: T): String = genericShow.value.show(genericT.to(t))
	}
}

object Test {
	import GeneralShow._

	implicitly[Show[Int :: String :: HNil]]

	case class Foo(i: Int, s: String)
	case class Bar(f: Foo)
	implicitly[Show[Bar]]
}