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