LiteralValue.scala

abstract class LiteralValue[S] {
  def value: S
}

object LiteralValue {
  def apply[S](implicit ev: LiteralValue[S]): LiteralValue[S] = ev

  implicit def makeLiteralValue[S <: Singleton]: LiteralValue[S] =
    macro LiteralValueMacros.makeLiteralValue[S]
}

class LiteralValueMacros(val c: Context) {
  import c.universe._

  def makeLiteralValue[S <: Singleton](
    implicit S: c.WeakTypeTag[S]
  ): c.Expr[LiteralValue[S]] = S.tpe.dealias match {
    case ConstantType(const) =>
      c.Expr[LiteralValue[S]](q"""
        new LiteralValue[$S] {
          override val value: $S = ${Literal(const)}
        }
      """)
    case tpe => c.abort(c.enclosingPosition, s"$tpe isn't a singleton type")
  }
}