#15628: Higher-rank kinds -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.6.1-beta1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Instantiating a polymorphic type variable with a polytype (or polykind) is called "imprediative polymorphism" and is a swamp. GHC just does not have a decent story at the moment. But I think that is what you are asking for. But see https://www.microsoft.com/en-us/research/publication/guarded- impredicative-polymorphism/ (PLDI'18). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15628#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler