We've had quite a bit of discussion lately on the difficulty in performing automated processing of Haskell files in the presence of CPP. It turns out that folks have tackled this sort of problem in the world of C, and done some interesting work. I recently ran across SuperC [1], part of the xtc [2] project. In the setting of C they have achieved some impressive results, including as I understand it, the ability to handle the entire Linux kernel across all CPP-recognized configurations. They note that this is a rather tedious to implement task, even once one has recognized the specification of how to do so. However, the paper is good at reviewing related work and simpler techniques as well, and perhaps among them there is a "good enough" set for the CPP used in common Haskell libraries? Cheers, Gershom [1] https://cs.nyu.edu/rgrimm/papers/pldi12.pdf [2] http://cs.nyu.edu/xtc/