#13192: Ambiguity Caused By PolyKind and Not Helpful Error Messages -------------------------------------+------------------------------------- Reporter: Shayan-Najd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by rwbarton): Why does it also not work if I change the definition of `F` to {{{ type family F (x :: *) :: k }}} in which case ghci tells me the instance is {{{ type instance F k (I k a) = a -- Defined at I.hs:7:16 }}} but ghc gives the same error regarding `identity`. Is `k` not determined by the result kind of the type family, i.e., the fact that `F (I a)` appears as a type argument to `(->)`? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13192#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler