[Haskell-cafe] Find unused exports

Hello, Has anyone already made a tool to check if exported functions, data constructors, types, etc are unused within a set of modules? For my usage it would probably suffice if the tool only compared import lists against export lists as we compile with -Wall and 99% of our imports say exactly which names are imported (and that last 1% could easily be fixed to say as well). If the tool doesn't already exist is there an easy way to approximate it? Thanks, Jason