While browsing the source code of the Scala API, I met this package definition in scala/tags/R_2_8_0_final/src/library/scala/util/parsing/combinator/syntactical/StdTokenParsers.scala:
package scala.util.parsing
package combinator
package syntactical
What does that mean? That the class will be available in more than one package?
This is basically the same as
package scala.util.parsing.combinator.syntactical
import scala.util.parsing._
import scala.util.parsing.combinator._
...
So by "stacking" the packages the way you wrote you can get super-packages in scope. See also these answers.
[Update] Here is a new article written by Martin Odersky about this topic: http://www.artima.com/scalazine/articles/chained_package_clauses_in_scala.html
The Scala reference mentions (chapter 9, section 9.1):
A compilation unit consists of a sequence of packagings, import clauses, and class and object definitions, which may be preceded by a package clause.
A compilation unit
package p1; ... package pn; statsstarting with one or more package clauses is equivalent to a compilation unit consisting of the packaging
package p1 { ... package pn { stats } ... }
See also Organizing Code in Files and Namespaces on nested packages.
(From Programming Scala: Scalability = Functional Programming + Objects
By Dean Wampler, Alex Payne, page 44, Chapter 2)
