Hi all, I got some prepocessor constrains in one of my library I use for my new project. The section look like this: ... #ifdef DEBUG [ppSig sig | sig <- sigs ] #else [ppSig sig | sig <- filter ((\(_,_,r) -> not r) . lhsRootSym) sigs ] #endif ... Due to the reason that I am still developing wanted to specify the DEBUG preprocessor symbol to cpphs, gcc, ghc, or whatever program needs it. My suggestion was that cpphs should handle these definitions. So I tried several things, like: cabal configure --cpphs-options="--cpp -DDEBUG" --ghc-options=-DDEBUG --gcc-options=-DDEBUG && cabal build && cabal install , cabal configure --cpphs-options="-DDEBUG" --ghc-options=-DDEBUG --gcc-options=-DDEBUG && cabal build && cabal install or cabal configure && cabal build --cpphs-options="--cpp -DDEBUG" --cpphs-options=-DDEBUG --gcc-options=-DDEBUG && cabal install I tried it also in the cabal file: default-extensions: CPP -- also tried with other-extensions if flag(debug) CPP-Options: -DDEBUG if !os(windows) CC-Options: -DDEBUG else CC-Options: -DNDEBUG and compiling with cabal configure --flags=debug && cabal build && cabal install. None of them worked. Am I doing it wrong, or is there something wrong with cabal, cpphs, ghc, etc. Thanks for your reply, Manuel -- To reply secure use GnuPG encryption: Key Block to use (http://www.pinselzone.com/pgp/public_gpg_key.asc) What is GnuPG? (http://www.gnupg.org/)