gistfile1.scala

scala> val l = List(10, 100, 1000, 10000)
l: List[Int] = List(10, 100, 1000, 10000)

scala> l.orElse[Int, Int]{ case i: Int => 34 }
res14: PartialFunction[Int,Int] = <function1>

scala> res14(0)
res15: Int = 10

scala> res14(10)
res16: Int = 34

scala> l.map(_ * 2).orElse[Int, Int]{ case i: Int => 34 }
res17: PartialFunction[Int,Int] = <function1>

scala> res17(10)
res18: Int = 34

scala> l.map(_.toString.length).orElse[Int, Int]{ case i: Int => 34 }
res19: PartialFunction[Int,Int] = <function1>

scala> res19(10)
res20: Int = 34

scala> l.map(_.toString).orElse[Int, String]{ case i: Int => "bah" }
res21: PartialFunction[Int,String] = <function1>

scala> res21(10)
res22: String = bah