Type safety!

gistfile1.scala

scala> val foo = Map("one" -> List("one", "two"))
foo: scala.collection.immutable.Map[String,List[String]] = Map(one -> List(one, two))

scala> foo.get("one").asInstanceOf[Option[Int]]
res1: Option[Int] = Some(List(one, two))

scala> val bar:Option[Int] = Some(List("one", "two"))
<console>:7: error: type mismatch;
 found   : List[String]
 required: Int
       val bar:Option[Int] = Some(List("one", "two"))