#14147: Confusing error messages with PolyKinds and superclasses -------------------------------------+------------------------------------- Reporter: enolan | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by enolan): OK, I'm willing to accept that code that compiles without `PolyKinds` shouldn't necessarily compile with it turned on. I still think this is a bad error message though. Yes, `k` is a variable that exists, but it's not one I wrote. From the user's perspective this message is very unhelpful. Perhaps something along these lines could be appended to the message when an error like this is emmited: "where k is an inferred kind parameter in Tagged's kind: `forall {k}. k -> * -> *`". Then I'd know where `k` comes from and can figure out that I can add a `Typeable` constraint for it or fix it at `*`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14147#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler