#5217: GADT declaration not (yet) handled by Template Haskell
----------------------------------------+-----------------------------------
Reporter: Ashley Yakeley | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 7.0.3
Resolution: fixed | Keywords:
Testcase: th/T5217 | Blockedby:
Difficulty: | Os: Unknown/Multiple
Blocking: | Architecture: Unknown/Multiple
Failure: GHC rejects valid program |
----------------------------------------+-----------------------------------
Changes (by simonpj):
* status: new => closed
* testcase: => th/T5217
* resolution: => fixed
Comment:
I've fixed this. I did not need to extend TH syntax, because it's already
rich enough to do the job (cf #4188).
{{{
commit 5c4a4c4bfe2a007f41f42ebab689bcd7219bed0d
Author: Simon Peyton Jones <[email protected]>
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(-)
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5217#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
