#10056: Inconsistent precedence of ~ -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 (Parser) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: #10059 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): I'm not aware of anyone disagreeing, so I don't think that's an obstacle. I attempted to fix this at one point, but I wasn't experienced enough in GHC to come up with a solution. One huge obstacle (for me, anyway) is that GHC co-opts the tilde symbol for [http://git.haskell.org/ghc.git/blob/1e041b7382b6aa329e4ad9625439f811e0f27232... laziness annotations], which means that all occurrences of `~` as type equalities are converted via a [http://git.haskell.org/ghc.git/blob/5f1e42f22cf29bc1b7150e06b2711fa7c43c6e5b... special parser function]. This makes it much harder to remove `~` as a special parser case, and when I tried removing it, it ended up introducing an enormous number of shift-reduce conflicts. I would also like to see this fixed at some point, but I don't think I'm going to be the one to fix it. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10056#comment:25 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler