#10832: Generalize injective type families -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: jstolarek Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.11 checker) | Keywords: TypeFamilies, Resolution: | InjectiveFamilies Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #6018 | Differential Rev(s): Phab:D1287 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): I haven't found so many uses for this, but I wanted to try this lately {{{#!hs -- Free :: (Type -> Constraint) -> (Type -> Type) -- Forget :: (Type -> Constraint) -> (Type -> Type) newtype Free cls a = Free (forall xx. cls xx => (a -> xx) -> xx) type family Forget cls free = res | res cls -> free where Forget cls (Free cls a) = a }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10832#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler