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

[Tim Baumgartner]

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