Hi café, I'm working on a small project, and I need to rename all ocurrences of a data type in a module. For instance, if the program is module Foo where data Bar fun :: Bar -> Bar fun = ... I'd like that during compilation the module looks as if it was written like: module Foo where data _BarXZY fun :: _BarXZY -> _BarXZY fun ... I think the simplest way to do this is using TH to define a special $data splice, which directly mangles the name. But then I'd need another splice every time I want to use the type. I've read other options like implementing a GHC compiler plugin ( http://www.haskell.org/ghc/docs/7.2.1/html/users_guide/compiler-plugins.html ) is it possible to perform the renaming by modifying the ModGuts structure in a compiler pass? Can you please give more pointers on how to perform this task? Thanks -- Ismael