#7643: Kind application error -----------------------------+---------------------------------------------- Reporter: gmainland | Owner: Type: bug | Status: new Priority: normal | Component: Compiler (Type checker) Version: 7.6.1 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: #7354 -----------------------------+---------------------------------------------- Changes (by shachaf): * related: => #7354 Comment: I reduced the test case a bit: {{{ {-# LANGUAGE MagicHash, TypeFamilies #-} module T7643 where import GHC.Exts type family T type instance T = RealWorld foo :: () -> State# T foo _ = unsafeCoerce# realWorld# }}} The `unsafeCoerce#`ed type actually matches -- but GHC has a problem with `State# RealWorld ~ State# T` (this isn't specific to `State#` or `RealWorld` -- unboxed tuples etc. work too. The issue is with the kinds). This seems to be a variety of #7354, but it's still broken in HEAD because of the kind issue. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7643#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler