#3497: Template Haskell support for GADTs
------------------------------+---------------------------------------------
Reporter: simonpj | Owner:
Type: feature request | Status: closed
Priority: normal | Milestone: 7.0.1
Component: Compiler | Version: 6.10.4
Resolution: fixed | Keywords:
Testcase: | Blockedby:
Difficulty: Unknown | Os: Unknown/Multiple
Blocking: | Architecture: Unknown/Multiple
Failure: None/Unknown |
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Changes (by simonpj):
* status: new => closed
* resolution: => fixed
Comment:
OK this is done:
* For reifying instances see #1480
* For GADTs, TH syntax is now expressive enough to reify GADTs, albeit
slightly oddly. A GADT
{{{
data Con = NormalC Name [StrictType] -- ^ @C Int a@
| RecC Name [VarStrictType] -- ^ @C { v :: Int, w :: a
}@
| InfixC StrictType Name StrictType -- ^ @Int :+ a@
| ForallC [TyVarBndr] Cxt Con -- ^ @forall a. Eq a => C
[a]@
}}}
The `ForallC` form of constructor can express GADTs because the `Cxt` can
include equality constraints.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3497#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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