#2893: Implement "Quantified contexts" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: proposal 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): Has there been any discussion about GHC generating instances of [https://hackage.haskell.org/package/constraints-0.8/docs/Data- Constraint.html#t::-61--62- :=>] and [https://hackage.haskell.org/package/constraints-0.8/docs/Data- Constraint.html#t:Class Class]: {{{#!hs -- Given -- class Foo a => Bar a -- GHC should generate -- instance Class (Foo a) (Bar a) where -- cls :: Bar a :- Foo a -- cls = Sub Dict class Class b h | h -> b where cls :: h :- b }}} or [https://hackage.haskell.org/package/constraints-0.8/docs/Data- Constraint-Lifting.html#t:Lifting Lifting] {{{#!hs class Lifting p f where lifting :: p a :- p (f a) class Lifting2 p f where lifting2 :: p a :- Lifting p (f a) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/2893#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler