shapeless_witnesses.scala

import shapeless.syntax.std.tuple._
import shapeless._, syntax.singleton._

object ShapelessMain {

  def main(args: Array[String]): Unit = {
    val l = 23 :: "foo" :: true :: HNil
    l(1)
    val t = (23, "foo", true)
    t(1)
    23.narrow
    "foo".narrow

    val (wTrue, wFalse) = (Witness(true), Witness(false))

    type True = wTrue.T
    type False = wFalse.T

    trait Select[B] {
      type Out
    }

    implicit val selInt = new Select[True] {
      type Out = Int
    }

    implicit val selString = new Select[False] {
      type Out = String
    }

    def select[T](b: WitnessWith[Select])(t: b.Out) = t

    select(true)(23)

//    select(true)("foo")
//    select(false)(23)
    select(false)("foo")

  }
}