Perhaps I should have post this as my first message to the group, but I will add it anyway for completeness. Or in case someone wants to try Scala out and at least you can grap this template to start pasting code to trying it out for other examples.

object Hello {
  def main(args: Array[String]): Unit = {

    println("Hello world.")

  }

}

Save above into Hello.scala, then compile and run your program like these:

powerbookg4:tmp zemian$ scalac Hello.scala
powerbookg4:tmp zemian$ scala Hello

Hello world.

Note that Scala main entry program is a "object" instead of "class". "object" in Scala is like a class that define a type, but it force it to be a singleton(only one instance), so it almost like "static" in Java. Your main entry in command line must be an object with the main method defined.

You may turn your source file into a script by enter a expression that invoke the main method on the end of the file, and then run it through "scala" instead of compiling it. For example:

object Hello {
  def main(args: Array[String]): Unit = {

    println("Hello world.")

  }

}

Hello.main(args)

Note that variable "args" is predefined when you run it as script. To run it, just invoke like this:

powerbookg4:tmp zemian$ scala Hello.scala
Hello world.

Note the difference. 1 no compile. 2 you give scala the script file name, not the type name!

Happy programming!