#14728: Is (GeneralizedNewtypeDeriving + associated type classes) completely bogus? -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.2 checker) | Keywords: deriving, Resolution: | TypeFamilies 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 goldfire): Good about generating Core for type instances. Then this is all doable today. `axIdentity` is the newtype axiom that comes into being when a user declares a newtype. It can be accessed by `coerce`, but is mostly internal magic. Specifically, if you write {{{ newtype N a b c = MkN (some_type) }}} then we get {{{ axN :: N a b c ~R some_type }}} as an axiom (type `CoAxiom` in GHC). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14728#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler