I realize ActionScript, like some other dynamic languages, have optional type declarations.
I don't care for static types, optional or not, declared or not. If you want speed, there's other ways to get it. If you want safety, there's other ways to get better safety. If you want documentation, they document the wrong thing.
Alan Kay pointed out a long time ago the benefit of message passing and "duck typing" if you will. I am a huge fan.