Re: [Haskell-cafe] Request: warn about language extensions that are not used

2009/3/11 Peter Verswyvelen :

When I put {-# OPTIONS_GHC -Wall -Werror #-} in my source file, I don't get compiler (GHC) warnings about redundant language extensions that I enabled. It would be nice if the compiler gave warnings about this, since after refactoring, some language extensions might not be needed anymore, and hence should be removed since fewer language extensions mean more stable and portable code no? What do you think?

So you mean something like if you put {-# LANGUAGE GeneralizedNewtypeDeriving #-} in a file, but never do newtype deriving, it would warn you? I have no idea how hard that'd be to implement, but that sounds kind of cool. Useful for both refactoring and when you've inherited old code. Cheers, C