[GHC] #8776: Displaying pattern synonym for a GADT

[GHC]

#8776: Displaying pattern synonym for a GADT
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        Reporter:  monoidal          |            Owner:  cactus
            Type:  bug               |           Status:  merge
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by cactus):

 I've wasted too much time trying to get it to work... While the general
 idea is sound, there's one tiny problem that unfortunately breaks the
 whole thing: `IfaceType`'s `ppr_ty` has no way of splitting an `IfaceType`
 into a theta and a tau, because `isIfacePredTy` is stubbed out:


 {{{
 isIfacePredTy :: IfaceType -> Bool
 isIfacePredTy _  = False
 -- FIXME: fix this to print iface pred tys correctly
 -- isIfacePredTy ty = isConstraintKind (ifaceTypeKind ty)
 }}}

 and there's no obvious way to implement `ifaceTypeKind` either...

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8776#comment:13>
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