[GHC] #7021: Tuple (and other exotic predicates) not yet handled in Template Haskell

[GHC]

#7021: Tuple (and other exotic predicates) not yet handled in Template Haskell
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        Reporter:        |            Owner:
  goldfire               |           Status:  new
            Type:        |        Milestone:  7.8.1
  feature request        |          Version:  7.5
        Priority:        |         Keywords:  ConstraintKinds
  normal                 |  TemplateHaskell
       Component:        |     Architecture:  Unknown/Multiple
  Template Haskell       |       Difficulty:  Unknown
      Resolution:        |       Blocked By:
Operating System:        |  Related Tickets:
  Unknown/Multiple       |
 Type of failure:        |
  None/Unknown           |
       Test Case:        |
        Blocking:        |
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Comment (by goldfire):

 Do you mean `TypeP` in your example?

 For my suggestion about making `Pred` a synonym of `Type`, we would need
 to add something like `EqualityT` to represent the poly-kinded equality
 predicate. Although this isn't a Haskell type, strictly speaking, there is
 already precedent for that in the constructors `StarT` and `ConstraintT`
 (which aren't types either).

 I'm not sure which of these options (the `TypeP` or the synonym approach)
 is the better and would love to hear others' thoughts.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7021#comment:4>
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