[Haskell-cafe] Unused definitions across modules in a package

Hey! GHC warns me about unused definitions in a module. However, is it possible to warn me about unused definitions in a package? For example, suppose that module A exports function f and that module B uses A.f (everything on a single package). However, after some time B stops using A.f. Is there a way of receiving a warning saying that "A exports f but no other module uses it."? (I know that this warning wouldn't be useful for libraries, since their whole point is to export things.) Cheers! -- Felipe.