Re: [Haskell-cafe] What features should an (fictitious) IDE for Haskell have?

very cool feature would be if I could select a program phrase and let it find /similar/ phrases, where a similarity metric could be edit-distance with respect to language tokens ...

I often wanted a tool that finds (nearly) duplicate AST sub-trees in a large code base, and suggests refactorings. Of course, in an IDE, it could alert me on-the-fly that I'm typing some code that's already present elsewhere. How might one go about implementing this? Actual (approximate) sub-tree matching seems the easy part; but I have no clear idea about whether this should just use syntax, or needs types as well (my guess is: yes) what libraries are there to provide the (annotated) ASTs, etc. - J.W.