Nope, at least not if you care about -Wall: If you take e.g. (<$>) which is now part of the Prelude, you can't simply import some compatibility module, because GHC might tell you (rightfully) that that import is redundant, because (<$>) is already visible through the Prelude. So you'll have to use CPP to avoid that import on base >= 4.8, be it from it Data.Functor, Control.Applicative or some compat-* module. And you'll have to use CPP in each and every module using <$> then, unless I miss something obvious. AFAICT all transitioning guides ignore -Wall and friends...