#14685: Pragma to reset language extensions in module header -------------------------------------+------------------------------------- Reporter: mgsloan | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In https://github.com/commercialhaskell/stack/issues/3789 , there is an issue where if OverloadableStrings is enabled in default extensions, the Paths_ module generated by cabal no longer compiles. I've opened a fix here - https://github.com/haskell/cabal/pull/5054 . However, this just disables specific extensions known to be problematic. It would be better to have a pragma that says "Please reset the extensions used for this module". I propose {{{ {-# LANGUAGE_RESET Haskell2010 #-} }}} and {{{ {-# LANGUAGE_RESET Haskell98 #-} }}} This would also provide for quite a nice workaround for the most common source of trouble when loading multiple packages at once into ghci - default-extensions causing some code to no longer compile. See https://ghc.haskell.org/trac/ghc/ticket/10827 for more about this. With `LANGUAGE_RESET`, we could write packages that gracefully load along with other packages that specify default-extensions. Of course, this is open to name bikeshedding. `{-# SET_LANGUAGE Haskell98 #-}`? Or perhaps just straight up `{-# HASKELL_98 #-}`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14685 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler