ActionScript 3 - Hello World Application

The following is a simple "Hello World" application written in ActionScript 3, and compiled into a .swf using mxmlc complier.

Files required...
Greeter.as
HelloWorld.mxml

Compile these two files into...
HelloWorld.swf

Code for Greeter.as
package
{
   public class Greeter
   {
      public function sayHello():String
      {
         var greeting:String;
         greeting = "Hello World!";
         return greeting;
      }
   }
}

Code for HelloWorld.mxml
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*"
layout="vertical"
creationComplete = "initApp()" >

<mx:Script>
     <![CDATA[
      private var myGreeter:Greeter = new Greeter();

      public function initApp():void
      {
         // says hello
         mainTxt.text = myGreeter.sayHello();
      }
      ]]>
</mx:Script>

<mx:TextArea id = "mainTxt" width="400" />
</mx:Application>