This may be a silly question, but I can't seem to find the answer in the documentation. I would like to create a Cabal package where some of the source files use a custom pre-processor. The pre-processor is itself a Haskell program, let's say MyPreProc.hs in the package's root directory. I figured out how to activate the preprocessor, for example, cabal build --ghc-options="-F -pgmF ./MyPreProc" I also figured out how to achieve the same effect using hooks. However, there is one problem: how can I tell cabal to actually compile MyPreProc.hs before any of the commands using the preprocessor are run? The package's Setup.hs file is automatically compiled during "cabal configure". I would like MyPreProc.hs to be compiled at the same time as well - or at least some time before the proprocessor needs to be used. The .cabal file contains all kinds of related variables, such as "build-depends" (but only packages can be listed here, not programs to be compiled), "other-modules" (but these modules would already require the pre-processor, so the pre-processor should be compiled first), "build-tools" (but this only refers to external programs). My current solution is to make the pre-processor a shell script, rather than a Haskell program. But this is ugly and not portable (won't work in Windows, for example). To clarify: my custom preprocessor is local to this package. It has no independent value, so it would not make sense to publish it as a separate package just so that I can add it to build-depends. Is there a known solution to this problem? Thanks, -- Peter