Implementing Generics, and none scalar default properties.

A couple of things that would really help me in PHP are generics and the ability to set default values of properties to instances of objects or calls to static methods or functions (expressions in general). I don't know if either of these have experimental implementations already as I couldn't find any, but if it would add some interest I may be willing to tackle the source to help push it forward. Could you please advise me on any fatal barriers that might prevent this being worth while for me. Thank you. Dominic