[GHC] #8165: Use GeneralizedNewtypeDeriving to automatically create associated type families

[GHC]

#8165: Use GeneralizedNewtypeDeriving to automatically create associated type
families
-------------------------------------+-------------------------------------
        Reporter:  MikeIzbicki       |                Owner:  RyanGlScott
            Type:  feature request   |               Status:  patch
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  7.6.3
  checker)                           |
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #2721             |  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/8165#comment:23>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler