[commit: ghc] master: Make TH capable of quoting GADT declarations (Trac #5217) (5c4a4c4)

[Simon Peyton Jones]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/5c4a4c4bfe2a007f41f42ebab689bcd7219bed0d

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

commit 5c4a4c4bfe2a007f41f42ebab689bcd7219bed0d
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jun 11 16:44:07 2011 +0100

    Make TH capable of quoting GADT declarations (Trac #5217)
    
    Template Haskell doesn't support GADTs directly but
    we can use equality constraints to do the job. Here's
    an example of the dump from splicing such a declaration:
    
        [d| data T a b
                where
                  T1 :: Int -> T Int Char
                  T2 :: a -> T a a
                  T3 :: a -> T [a] a
                  T4 :: a -> b -> T b [a] |]
      ======>
        T5217.hs:(6,3)-(9,53)
        data T a[aQW] b[aQX]
            = (b[aQX] ~ Char, a[aQW] ~ Int) => T1 Int |
              b[aQX] ~ a[aQW] => T2 a[aQW] |
              a[aQW] ~ [b[aQX]] => T3 b[aQX] |
              forall a[aQY]. b[aQX] ~ [a[aQY]] => T4 a[aQY] a[aQW]

 compiler/deSugar/DsMeta.hs      |  110 +++++++++++++++++++++++++++++----------
 compiler/hsSyn/HsTypes.lhs      |   14 +++++
 compiler/typecheck/TcHsType.lhs |   19 +------
 compiler/typecheck/TcMType.lhs  |    5 +-
 4 files changed, 102 insertions(+), 46 deletions(-)


Diff suppressed because of size. To see it, use:

    git show 5c4a4c4bfe2a007f41f42ebab689bcd7219bed0d