Question

I have seen in a few libraries, Spray for example, dual package specifications like this:

package cc.spray
package http

// code

Is this just eye candy for package cc.spray.http, or is there a functional benefit to breaking the two apart like this?

Answer 1

That is equivalent to this:

package cc.spray.http
import cc.spray._
// implicitly, import cc.spray.http._

That is, every member of package cc.spray and of package cc.spray.http are visible. On the other hand, members of the package cc are not visible.

This way one can safely use names such as java in their package hierarchy without causing trouble, and, at the same time, easily make visible the package scopes one wants to be visible.