#14840: QuantifiedConstraints: Can't define class alias -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.5 Resolution: fixed | 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: | -------------------------------------+------------------------------------- Changes (by Iceland_jack): * status: new => closed * resolution: => fixed Comment: Thanks! And comment:1 works with tricks but probably isn't much use once defined {{{#!hs class (a => b) => (a |- b) instance (a => b) => (a |- b) class (forall xx. f xx |- g xx) => f |~ g instance (forall xx. f xx |- g xx) => f |~ g class (forall xx. f xx |- exists) => Exists1 f exists instance (forall xx. f xx |- exists) => Exists1 f exists class exists => Exists2 f exists instance exists => Exists2 f exists class (Exists1 f |~ Exists2 f) => Exists (f::k -> Constraint) where instance (Exists1 f |~ Exists2 f) => Exists (f::k -> Constraint) where }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14840#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler