#6118: Kind variable falls out of scope in instance declaration -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.5 Resolution: fixed | Keywords: PolyKinds Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | polykinds/T6118 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): 8.1.20160503: {{{#!hs -- twgv.hs:32:3-43: error: … -- The RHS of an associated type declaration mentions ‘k’ -- All such variables must be bound on the LHS -- Compilation failed. instance SingE (a :: Maybe k) where type Demote a = Maybe (Demote (Any :: k)) }}} Still fails, kind annotation needed: {{{#!hs instance SingE (a :: Maybe k) where type Demote (a ::Maybe k) = Maybe (Demote (Any :: k)) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/6118#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler