#9301: Rank-2 constraints are assigned kind * -------------------------------------+------------------------------------ Reporter: heisenbug | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: duplicate | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by heisenbug): * status: new => closed * resolution: => duplicate Comment: This very much looks like a duplicate of #9196, closing. But my point is that I'd like to have polymorphic (multiparameter) constraints, where the param universally abstracted over is a non-`*` kind, that is an ADT. See: {{{ class Foo a where ... data Bar (b :: Bool) x = ... instance Foo (Bar True x) where ... instance Foo (Bar False x) where ... test :: (forall b. Foo (Bar b x)) =>... }}} Here the `forall` condition is satisfiable, as all `Bool` alternatives are covered with `instance` declarations. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9301#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler