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

24 Oct 2016

      #8165: Use GeneralizedNewtypeDeriving to automatically create associated type
families
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        Reporter:  MikeIzbicki       |                Owner:  goldfire
            Type:  feature request   |               Status:  new
        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):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Hm... what code would generated in this example?

 {{{#!hs
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE TypeFamilies #-}

 import Data.Kind

 class C (a :: k) where
   type T k :: Type

 instance C Int where
   type T Type = Int

 --------------------

 newtype MyInt = MyInt Int
   deriving C
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8165#comment:14
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