gistfile1.scala

intermediateLocations match {
        case Nil =>
          f(oDeparture, tArrival)
        case intermediate :: Nil =>
          f(oDeparture, iArrival(intermediate))
          f(iDeparture(intermediate), tArrival)
        case _ =>
          f(oDeparture, iArrival(intermediateLocations.head))
          val last = intermediateLocations.sliding(2).
            foldLeft(intermediateLocations.head) {
              case (last, i1 :: i2 :: Nil) =>
                f(iDeparture(i1), iArrival(i2))
                i2
              case _ => sys.error("Non-exhaustive match here")
            }
          f(iDeparture(last), tArrival)
      }