OMG! I still have 7.6.3. It has old Typeable. I misunderstood PolyKinds a bit. It looks like k /= **, k ~ *******... But we cannot use "CloseKinds" like data Foo (a::k) = Foo a -- catch an error "Expected kind `OpenKind', but `a' has kind `k'" with RankNKinds we could write: data Foo (a::**) = Foo a data Bar (a::***) = Bar a So, now the task is more easy: I'm asking for useful examples with "CloseKinds" with ** and higher, and any useful examples for *** and higher cheers, Wvv 29 Jul 2013 at 14:44:50, José Pedro Magalhães [via Haskell] (ml-node+s1045720n5733561h30@n5.nabble.com) wrote: Hi, On Fri, Jul 26, 2013 at 10:42 PM, Wvv <[hidden email]> wrote: First useful use is in Typeable. In GHC 7.8 class Typeable (a::k) where ... <<==>> class Typeable (a ::**) where ... But we can't write data Foo (a::k)->(a::k)->* ... deriving Typeable Why not? This works fine in 7.7, as far as I know. Cheers, Pedro -- View this message in context: http://haskell.1045720.n5.nabble.com/Rank-N-Kinds-tp5733482p5733667.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.