gistfile1.scala

object Test extends App {
  case class Item[A, B](get: A => B, apply: B => Unit)

  def hlist[A] =
    Item((_: A) => 73, println) ::
      Item((_: A) => "hello", println) ::
      Item((_: A) => false, println) ::
      HNil

  class Combine[A] extends Poly2 {
    implicit def x[T <: HList, B] = at[A => T, Item[A, B]]((aggFunc: A => T, item: Item[A, B]) => { a: A => item.get(a) :: aggFunc(a) })
  }
  object combine extends Combine[Double]

  val items = hlist[Double]
  val f1 = items.foldLeft((_: Double) => HNil)(combine)

  implicitly[f1.type <:< (Double => (Boolean :: String :: Int :: HNil))]

  val res = f1(32.0)

  implicitly[res.type <:< (Boolean :: String :: Int :: HNil)]

  assert(res == (false :: "hello" :: 73 :: HNil))

  object apply extends Poly1 {
    implicit def default[T] = at[Item[_, T]](_.apply)
  }

  val zipped = items zip res.reverse

  implicitly[zipped.type <:< ((Item[Double, Int], Int) :: (Item[Double, String], String) :: (Item[Double, Boolean], Boolean) :: HNil)]
  //res map apply
}