in scala
trait Function0

abstract trait Function0 [R]
extends java.lang.Object
with scala.ScalaObject
Function with 0 parameters. In the following example the definition of currentSeconds is a shorthand for the anonymous class definition anonfun0:
 object Main extends Application {

   val currentSeconds = () => System.currentTimeMillis() / 1000L

   val anonfun0 = new Function0[Long] {
     def apply(): Long = System.currentTimeMillis() / 1000L
   }

   Console.println(currentSeconds())
   Console.println(anonfun0())
 }

Def Summary
abstract def apply : R

override def toString : java.lang.String

Def Detail
abstract def apply : R

override def toString : java.lang.String