#16013: :kind! accepts unsaturated type aliases -------------------------------------+------------------------------------- Reporter: dmwit | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here's a ghci session: {{{
:set -XTypeFamilies -XPolyKinds type family Id (a :: k) type instance Id a = a type Foo x = Maybe :kind! Id Foo Id Foo :: * = Id Foo }}}
I think the final `:kind!` query should throw an error instead, complaining that `Foo` hasn't been given enough arguments. (But even if you disagree, and think it should be allowed, `*` is clearly not the right kind!) Using a normal type alias in place of the type family for `Id` also allows the query incorrectly, though it does at least report a sensible kind. Although I think it shouldn't matter, I have checked with `-ignore-dot- ghci` to make sure I haven't accidentally turned LiberalTypeSynonyms on. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16013 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler