I am currently working on an alternative implementation of the STM monad and would like to keep my work as isolated as possible. To that end, I have tried to keep all my files separate in a confined package. The package consists of haskell files which are exported to the programmer, a C-- file which is used by the haskell functions, and a C file, which is called from some of the C-- primitives. Inside my C file, I need to call a couple of functions that exist in the RTS, such as "dirty_TVAR" from (rts/sm/Storage.h). Is there a good way to include this header file in my C file? I would like to be able to list rts/sm in my cabal file under Include-Dirs. I'm wondering if there is something analogous to an environment variable or anchor names (from SML/NJ compilation manager) that can tell me where the GHC source directory root is. As an example, I would like to do something to the effect of: library Include-Dirs: $GHC_ROOT/rts, $GHC_ROOT/rts/sm where $GHC_ROOT would tell cabal where to find the ghc source directory in the file system. I tried giving a relative path (which as expected does not work), giving the following warning: Warning: 'include-dirs: ../../rts' is a relative path outside of the source tree. This will not work when generating a tarball with 'sdist'. I can give an absolute path for my machine and everything compiles just fine, but this is obviously not portable. Any help would be much appreciated. -Matt