#8566: Given kind equalities are discarded -------------------------------------+------------------------------------ Reporter: dreixel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: polykinds/T8566 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by goldfire): I'm fine with your last suggestion, but I wonder if there's a different way: instead of rejecting the constructor, what if the "bad error messages" suggest the nature of the problem? For example, if a type error occurs after dropping an unusable given kind equality, that error message could say what kind equality was dropped and why. (This is somewhat like error messages that warn about ambiguous variables.) I would imagine that the folks who write the weirdly-existential constructors would be able to understand such a message and respond appropriately. Would this be an engineering challenge (that is, remembering the dropped given equality, just for error reporting)? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8566#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler