17 Dec 17:21
GADT pattern match in non-rigid context
From: Neil Mitchell <ndmitchell <at> gmail.com>
Subject: GADT pattern match in non-rigid context
Newsgroups: gmane.comp.lang.haskell.glasgow.user
Date: 2007-12-17 16:23:24 GMT
Subject: GADT pattern match in non-rigid context
Newsgroups: gmane.comp.lang.haskell.glasgow.user
Date: 2007-12-17 16:23:24 GMT
Hi,
Upgrading from GHC 6.6 to 6.8 has caused some code to stop working:
----------------------------------------------------------------------
{-# OPTIONS_GHC -fglasgow-exts #-}
module Data2 where
data CCompany
data Paradise :: * -> * where
CC :: Paradise CCompany
rewrapCC CC = []
----------------------------------------------------------------------
[1 of 1] Compiling Data2 ( Data2.hs, interpreted )
Data2.hs:12:9:
GADT pattern match in non-rigid context for `CC'
Tell GHC HQ if you'd like this to unify the context
In the pattern: CC
In the definition of `rewrapCC': rewrapCC CC = []
This code is from the Uniplate benchmarking code, which runs the
Paradise benchmark from SYB on Uniplate, Compos and SYB. The Compos
code uses GADT's, so the program first needs to convert from standard
data structures to GADT's before it can work, then back at the end.
It's the problem of converting from a GADT to a normal data structure
(Continue reading)
Neil
>
> | -----Original Message-----
> | From: glasgow-haskell-users-bounces <at> haskell.org
[mailto:glasgow-haskell-users-bounces <at> haskell.org] On Behalf Of
> | Neil Mitchell
> | Sent: 17 December 2007 16:23
> | To: glasgow-haskell-users <at> haskell.org
> | Subject: GADT pattern match in non-rigid context
> |
> | Hi,
> |
> | Upgrading from GHC 6.6 to 6.8 has caused some code to stop working:
> |
> | ----------------------------------------------------------------------
> | {-# OPTIONS_GHC -fglasgow-exts #-}
> |
> | module Data2 where
> |
> | data CCompany
> |
> | data Paradise :: * -> * where
> | CC :: Paradise CCompany
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