#2721: Newtype deriving doesn't work with type families -------------------------------------+------------------------------------- Reporter: rl | Owner: Type: feature request | Status: patch Priority: lowest | Milestone: 8.2.1 Component: Compiler (Type | Version: 6.10.1 checker) | Resolution: | Keywords: TypeFamilies Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | deriving/should_fail/T2721 Blocked By: | Blocking: Related Tickets: #8165 | Differential Rev(s): Phab:D2636 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott <ryan.gl.scott@…>): In [changeset:"630d88176e8dd3ccc269451bca8f55398ef5265c/ghc" 630d8817/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="630d88176e8dd3ccc269451bca8f55398ef5265c" Allow GeneralizedNewtypeDeriving for classes with associated type families Summary: This implements the ability to derive associated type family instances for newtypes automatically using `GeneralizedNewtypeDeriving`. Refer to the users' guide additions for how this works; I essentially follow the pattern laid out in https://ghc.haskell.org/trac/ghc/ticket/8165#comment:18. Fixes #2721 and #8165. Test Plan: ./validate Reviewers: simonpj, goldfire, austin, bgamari Reviewed By: simonpj Subscribers: mpickering, thomie Differential Revision: https://phabricator.haskell.org/D2636 GHC Trac Issues: #2721, #8165 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2721#comment:26> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler