You should sort out how to use cabal sandboxing http://www.haskell.org/cabal/users-guide/installing-packages.html#developing-with-sandboxes http://www.haskell.

You should sort out how to use cabal sandboxing http://www.haskell.org/cabal/users-guide/installing-packages.html#developing-with-sandboxes http://www.haskell.org/cabal/users-guide/installing-packages...