#14958: QuantifiedConstraints: Doesn't apply implication for existential? -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Resolution: | Keywords: | QuantifiedConstraints, wipT2893 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 Iceland_jack): Ah! That makes perfect sense, we can specify a `Proxy cls` and not change the kind of `Foo` although I'm not sure this gives me what I want {{{#!hs data Foo where Foo :: Proxy cls -> (forall x. ((forall y. cls y => Num y), cls x) => x) -> Foo a :: Foo a = Foo (Proxy :: Proxy Num) 10 b :: Foo b = Foo (Proxy :: Proxy Fractional) 10.0 }}} I have a draft ready for an overview of this extension from ticket:14840#comment:6, should I email it to you? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14958#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler