Hi Eric
I thought about that. But consider the following scenario. We have a Dispatcher and a Handler. The Dispatcher sends messages to Handlers. There are two ways we could implement this in an OOP language
"Consider how to implement OO features in Haskell"... Lets not, rather instead lets try to come up with a much cleaner and more Haskell-like by design. You can do imperative programming and OO programming in Haskell, in the same way you can do functional programming in ASM - possible but not a great idea. Thinking in Haskell requires you to peel away all the layers of OO, right back to the original thoughts about what you want to happen. Rather than sending a message from the dispatcher to the handler, and have a general purpose handler, why not instead register functions as callbacks? registerOnClick :: (Coordinates -> IO ()) -> IO () registerOnClose :: (Bool -> IO()) -> IO () Now you have absolutely no restriction on what information a "message" contains. (Note: you haven't given enough information to know if this suits your problem, but dynamic typing isn't the best answer, whatever the question!) Thanks Neil