gistfile1.scala

object Obs {

  import shapeless._, poly._
  import shapeless.ops.tuple.Mapper


  object values extends (Obs ~> Id) {
    def apply[T](t: Obs[T]) = t.value
  }

  case class Calculate[O, T](observables: O, mapper: Mapper.Aux[O, values.type, T]) {
    def withFun[Z](fun: T => Z): Z = fun(mapper(observables))
  }

  def calculate[O, T](observables: O)(implicit mapper: Mapper.Aux[O, values.type, T]) =
    Calculate(observables, mapper)
}

object ObsExample {
  import Obs._

  val obs1: Obs[Double] = ???
  val obs2: Obs[Option[Int]] = ???
  val obs3: Obs[String] = ???
  val obs4: Obs[List[Double]] = ???

  calculate(obs1, obs2) withFun {
    case (d, i) => d + i.getOrElse(0).toDouble
  }

  val f: (Option[Int], String, List[Double]) => String = ???

  calculate(obs2, obs3, obs4) withFun f.tupled

}