(scroll down for Haxe version)

AS3

//Package
package
{
    //Imports
    import flash.display.*
    import flash.events.*

    //Class definition
    public class Main extends MovieClip
    {
        //Class fields & types
        private var array:Array = ["hello", 10]
        private var boolean:Boolean = true
        private var integer:int = -10
        private var uinteger:uint = 10
        private var number:Number = 10.5
        private var object:Object = {foo:'bar'}
        private var string:String = '13'
        
        //Properties
        private var _sampleProperty:Object;
        public  function get sampleProperty():Object {
            return _sampleProperty;
                }

        public function set sampleProperty(value:Object):void {
            _sampleProperty = value;
        }

        //Constructor
        public function Main()
        {
            var _str:String = String(integer);
            var _int:int = int(string);

            for(var i:int=0; i<array.length; i++)
            {
                trace(array[i]);//Hello,World
            }
            with (object)
            {
                foo=10;
            }
            test('a');//a, b (falls through because of the missing break statement)
        }
        
        //Methods
        private function test(param:String):void
        {
            private function test(param:String):void
            {
                switch (param)
                {
                    case "a":
                        trace("a");
                    case "b":
                        trace ("b");
                        break;
                    default:
                        trace ("Neither")
                }
            }
        }
    }
}
//Private classes?

compile with:

mxmlc Main.as -output MovieAS3.swf

HAXE

//semicolons are mandatory
//Package
package;// no curly braces for package

//Imports
import flash.display.MovieClip;// no wildcard for imports
import flash.events.Event;
import flash.Lib;

//Class definition
class Main extends MovieClip// no 'public' keyword here
{
    //Class Fields & types
    // no variable instantiation outside functions
    private var array:Array<String>;//Arrays are typed
    private var boolean:Bool;
    private var integer:Int;
    private var uinteger:UInt;
    private var number:Float;
    private var object:Dynamic;
    private var string:String; 
    
    //Properties
    private var _sampleProperty:Dynamic;
    public var sampleProperty(getSampleProperty, setSampleProperty):Dynamic;

    public function getSampleProperty() {
        return _sampleProperty;
    }

    public function setSampleProperty(value:Dynamic) {
        _sampleProperty = value;
    }

    //Constructor
    public function new()//constructor name is always 'new'
    {
        super();// super is mandatory
        array = ["hello", "world"];
        boolean = true;
        integer = -10;
        uinteger = 10;
        number = 10.5;
        object = {foo:'bar'};
        string = '13';
        
        var _str:String = Std.string(integer);
        var _int:Int = Std.parseInt(string);

        for(i in 0...array.length)
        {
            trace(array[i]);//hello,world
        }
        
        for(i in array)
        {
            trace(i);//hello, world
        }
        //with(object){foo=10}// the with keyword is not available in Haxe

        test('a');//a (no break statements in the switch-case statements)
    }

    //Methods
    private function test(param:String):Void // Void (with capital)
    {
        switch (param)
        {
            case "a":
                trace("a");
            case "b":
                trace ("b");
            default:
                trace ("Neither");
        }
    }

    /***********************************************************************************************************************/
    //To tell the FlashPlayer what script should be run when opening the swf 
    //you need to supply a 'main entry point'. See the compiler argument -main below.
    public static function main()
    {
        flash.Lib.current.addChild(new Main());
    }
    /***********************************************************************************************************************/
}
//Private classes?

compile with:

Main
-main Main
-swf9 MovieHaxe.swf

Main : tells the compiler what class(es) must be compiled
-main Main: tells the compiler that the main entry point for the swf can be found inside the class Main
-swf9 MovieHaxe.swf: tells the compiler to generate an 'AS3-swf file' named MovieHaxe.swf

This page lists all the compiler arguments:
http://haxe.org/doc/compiler