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Diffstat (limited to 'src/library-aux/scala/Nothing.scala')
| -rw-r--r-- | src/library-aux/scala/Nothing.scala | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/library-aux/scala/Nothing.scala b/src/library-aux/scala/Nothing.scala new file mode 100644 index 0000000000..eed6066039 --- /dev/null +++ b/src/library-aux/scala/Nothing.scala @@ -0,0 +1,23 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2002-2010, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +package scala + +/** `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 `T`. + * + * 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. + */ +sealed trait Nothing + |