You can do this with a custom cabal build type, a non-trivial Setup.hs.  Cabal exposes a bunch of 'user hooks' that let you specify functions to be run at various stages of the compilation (such as pre-build, post-install, etc...).

See the API here for the hooks available:

  - http://www.haskell.org/ghc/docs/7.6.3/html/libraries/Cabal/Distribution-Simple-UserHooks.html

I use prebuild hooks quite a lot to pre-process GF files (for the grammatical framework); one relatively simple example is shown in my gfI8N package: https://github.com/creswick/gfI8N

Note that the cabal file uses `build-type: Custom` (which causes cabal to actually use the Setup.hs).

The relevant part of the Setup.hs is:

That should be enough to get you going -- now some cautions, and a minor rant ;)

Working with these hooks has lead me to /really/ want a way to express dependencies for Setup.hs files.  You *can not* use any hackage libraries in the definitions of these hooks and retain a portable build, because there is no way to indicate that the Setup.hs depends on such things. It used to be the case that you could assume that the dependencies of your library / executable would be visible, but with sandboxed builds that assumption is no longer valid. There's a cabal ticket for this feature here: https://github.com/haskell/cabal/issues/948

You should be able to rely on these packages (which shipped with ghc -- the versions will depend on the ghc version installed):

 

--Rogan