final abstract open class Nothing
Nothing is - together with scala.Null - at the bottom of Scala's type hierarchy.
Nothing is a subtype of every other type (including scala.Null); there exist
no instances of this type. Although type
Nothing is uninhabited, it is
nevertheless useful in several ways. For instance, the Scala library defines a value
scala.collection.immutable.Nil of type
List[Nothing]. Because lists are covariant in Scala,
this makes scala.collection.immutable.Nil an instance of
List[T], for any element of type
Another usage for Nothing is the return type for methods which never return normally. One example is method error in scala.sys, which always throws an exception.