[GHC] #10902: Refactor type families in Template Haskell

[GHC]

#10902: Refactor type families in Template Haskell
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        Reporter:  goldfire          |                Owner:  johnleo
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Template Haskell  |              Version:  7.11
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by johnleo):

 Proposal:

 In `ghc/libraries/template-haskell/Language/Haskell/TH/Syntax.hs` create a
 new data type:
 {{{#!hs
 data TypeFamilyBase = TypeFamilyBase Name [TyVarBndr] FamilyResultSig
 (Maybe InjectivityAnn)
 }}}

 In `data Dec` in the same file replace the definitions of
 `OpenTypeFamilyD` and `ClosedTypeFamilyD` with the following:
 {{{#!hs
 | OpenTypeFamilyD TypeFamilyBase
 | ClosedTypeFamilyD TypeFamilyBase [TySynEqn]
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10902#comment:4>
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