Haskell refactoring technique: make it compile by making it undefined(blog.patch-tag.com)
blog.patch-tag.com
Haskell refactoring technique: make it compile by making it undefined
http://blog.patch-tag.com/2009/10/26/haskell-refactoring-technique-make-it-compile-by-making-it-undefined/
That's still not the whole story, I think, but it's a tool going in the toolbox.