[commit: ghc-prim] no-pred-ty: Add a data type we can use to box up equality evidence for -XConstraintKind (c7623fc)

[Max Bolingbroke]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/ghc-prim

On branch  : no-pred-ty

http://hackage.haskell.org/trac/ghc/changeset/c7623fc11d5adc54d9b39fc83555dfecb0f639bd

>---------------------------------------------------------------

commit c7623fc11d5adc54d9b39fc83555dfecb0f639bd
Author: Max Bolingbroke <batterseapower at hotmail.com>
Date:   Tue Sep 6 17:31:50 2011 +0100

    Add a data type we can use to box up equality evidence for -XConstraintKind

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 GHC/Types.hs |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/GHC/Types.hs b/GHC/Types.hs
index 3303cda..8e1c11b 100644
--- a/GHC/Types.hs
+++ b/GHC/Types.hs
@@ -78,6 +78,13 @@ or the '>>' and '>>=' operations from the 'Monad' class.
 newtype IO a = IO (State# RealWorld -> (# State# RealWorld, a #))
 
 
+-- | A data constructor used to box up all unlifted equalities
+--
+-- The type constructor is special in that GHC pretends that it
+-- has kind (? -> ? -> Fact) rather than (* -> * -> *)
+data (~) a b = Eq# ((~#) a b)
+
+
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 -- Generic representations
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