#13592: Newtype type class with compiler generated instances -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: 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): In a way it's a subset of `Coercible` but I don't know if there is any way to specify that more forcefully than ''default signatures''.. a `Coercible` superclass '''might''' work if we use fundeps {{{#!hs class (Coercible on n, Coercible n on) => Newtype n on | n -> on where }}} or {{{#!hs class (Coercible (O n) n, Coercible n (O n)) => Newtype n where type O n pack :: O n -> n pack = coerce unpack :: n -> O n unpack = coerce }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13592#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler