Re: [Haskell-beginners] How to "insert" a cross reference into a tree structure

Thanks for the answers. It seems this is a point where I can't easily translate an OO program to Haskell. I was afraid this might be the case. In my job, I work with heavy use of EMF (Eclipse Modeling Framework, for Java) which allows editing of models like the MusicCollection with generic support for features like Displaying in lists/trees, Moving, Deleting, Creating new child elements, Undo/Redo, Drag & Drop, lazyness via proxies. I'd really like to have (or even implement) something similar in Haskell, but this seems to be a very difficult task. Regards Tim