jammer.scala

import com.twitter.finagle.{Filter, Service}
import com.twitter.util.{Await, Future}

case class Fruit(flavor: String)
case class Veggie(flavor: String)
case class Jam(flavor: String)

object Jammer extends Service[Veggie, Jam] {
  def apply(veg: Veggie) =
    Future value Jam(veg.flavor)
}

object FruitToVeg extends Filter[Fruit, Jam, Veggie, Jam] {
  def apply(fruit: Fruit, jammer: Service[Veggie, Jam]) =
    jammer(Veggie(fruit.flavor))
}

val fruits = "apple" :: "banana" :: "cherry" :: "durian" :: Nil
val jammer = FruitToVeg andThen Jammer

try {
  val jams = Await result {
    Future collect {
      fruits map { Fruit(_) } map {
        jammer(_) map { _.flavor }
      }
    }
  }

  println("Made some tasty jam: %s".format(jams.mkString(", ")))
} catch { case e =>
  println("Error: %s".format(e.getMessage))
}

:; bin/scala -i util/util-app -i finagle/finagle-core jammer.scala
Made some tasty jam: apple, banana, cherry, durian