On Wed, 2008-10-15 at 09:46 +0100, Simon Peyton-Jones wrote:
Right. I've finally fixed 2497; it was a typo, and while I thought I'd tested it, the test didn't tet that RULES compile without any flags.
That's great, thanks.
The story is that you should not need any funny RankN flags just to make RULES parse and typecheck. -XScopedTypeVariables gets set automatically inside a RULES pragma. This is what the discussion on #2497 claimed, but there was a bug in the impl.
And for people trying to make their code compatible with older ghc too, they can use this in their .cabal files: extensions: ScopedTypeVariables Which makes Cabal pass -XScopedTypeVariables for ghc-6.8 and for 6.6 and earlier is passes -fglasgow-exts. This is what the bytestring package is currently using (and no more ghc-options: -fglasgow-exts). Duncan