If you’re still leaning towards releasing your higher order functions library, I’d gladly contribute time to helping with documentation or testing. I have some array filtering classes of my own that might fit with such a library, too.

I was interested to see how you were going to modify sendButton.addEventListener(MouseEvent.CLICK, onSendButtonClicked);

but later you replaced it with sendButton.addEventListener(MouseEvent.CLICK, onSendForm);

ahh well.

guards are very general and there are absolutely better ways to solve specific cases.

I agree that filtering events is a pain in the butt. However in this particular case (handling keyboard events), a map approach seems to me a lot more concise (and thereby more elegant :D). Now let’s see if the comment system allows me to submit code in a legible way. For testing, I wrote this little class called KeyMapper: /** * @author stephan.bezoen */ public class KeyMapper { private var mMap : Object = new Object(); private var mStage : Stage;

public function KeyMapper (inStage:Stage) {
    mStage = inStage;
     mStage.addEventListener(KeyboardEvent.KEY_UP, handleKeyEvent);
}

public function setMapping (inKey:uint, inHandler:Function) : void {
    mMap[inKey] = inHandler;
}

public function die () : void {
    mMap = null;
    mStage.removeEventListener(KeyboardEvent.KEY_UP, handleKeyEvent);
}

private function handleKeyEvent(e : KeyboardEvent) : void {
    if (mMap[e.keyCode]) mMap[e.keyCode]();
}

}

As you can see in the KeyMapper.handleKeyEvent() function, the only comparison that is still needed, is to check whether a mapping is defined for the pressed key.

To use this in an application, do the following: var km : KeyMapper = new KeyMapper(stage); km.setMapping(Keyboard.ENTER, submit); km.setMapping(Keyboard.ESCAPE, cancel);

In my view, this approach really takes away the inner workings of the keyboard event system from the user. It’s easily readable, and very easy to extend when more keys have to be handled.

As for multiple asynchronous events, that is a place where guards could very well come in handy. Just have to get used to the term I guess :D

Ruben: Seems like I have to show you my Trampoline some day, it’s your ArrayTool on speed =)

It’s nice to see that there are others that are interested in higher order functions and functional programming in ActionScript. If you look at my blog archive I think there are one or two old posts about how to do away with loops by using functional programming concepts.

I have a small library that I use privately which contains implementations of useful higher order functions and functional programming concepts, one day I’m going to get around to writing about them too.