Re: [Haskell-cafe] Type extensions

G'day all. Quoting Thomas Davie :

Essentially I would like some sort of inderritance property for Haskell types, I often find myself wanting to for example extend a tree with black/white colouring, or later extend the tree with some sort of ID, etc.

Have you had a look at these? http://haskell.org/hawiki?IndirectComposite http://haskell.org/hawiki?DecoratingStructures Cheers, Andrew Bromage