[Haskell-cafe] Using a library in a executable within same cabal package

Hello, Not sure this question is totally on-topic. Please point me in the right direction if it is not. I would like to make a cabal package containing both an executable and several libraries, and link the main executable to the libraries produced in the build. It is not clear how I can achieve that from the documentation. I tried Extra-libraries option but it does not work. Thanks for your help -- Arnaud Bailly