Haskell extention and Implementing Callbacks with a list

Hello,

I've got two Ideas:

1) Add a haskell extention (wouldn't this be
possible?) that allows for equality for functions. 
Maybe only valid for IO() functions.  Say we have:

a :: IO ()

  We know that (a == a) but a doesn't equal anything
else.  This would make the unregister process much
neater.


2)  Would it not be possible to do callbacks with
lists?

button [ onClick := [messageBox "hi there"] ]

add a callback:

set myButton [ onClick :~ (/a -> newFunction:a) ]

And if the onClick function found it had an empty
list, it would unregister the callback with the
underlying library.


David J. Sankel