#13546: Kind error with type equality -------------------------------------+------------------------------------- Reporter: int-index | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: TypeInType 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 agree with GHC here. The problem is that `UnT` takes `k` as a parameter. It does ''not'' look at the kind at which its argument is used and return something of that kind. So, in the type of `tunt`, the first `T` is applied at an unknown kind, which is also the return kind of `UnT`. Of course, you want this to be `Symbol`, but GHC doesn't know this. Adding a kind signature fixes the problem: {{{#!hs tunt :: Dict (T (UnT (T "a") :: Symbol) ~ T "a") tunt = Dict }}} Please close the ticket if you agree with my analysis. Thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13546#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler