
#13018: TH-spliced pattern synonym declaration fails to typecheck -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Keywords: Resolution: | PatternSynonyms Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): I made these functions monadic not too long ago. Looking back through, it seems the only `RnM` action taken is `addErrAt` from `mixedVarsErr` (and the related `xoptM` call). It wouldn't be hard to augment the `FreeKiTyVars` structure to include a list of errors generated. Then, the whole lot of these functions could be made pure. This would seem to be an improvement -- especially in your case when you are not interested in error messages. Alternatively, I've recently run into the need to have functions be used in both `TcM` and `DsM`, but the only monadic action, again, was error generation. It might be reasonable to have a `ErrMonad` class with instances for both `TcM` and `DsM`; then these `extractXXX` functions could be generalized over that class. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13018#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler