#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 RyanGlScott): I'm leery about adding more magic classes to GHC, but fortunately, this magic already exists as `Data.Coerce.Coercible`: {{{#!hs import Data.Coerce pack :: Coercible on n => on -> n pack = coerce unpack :: Coercible n on => n -> on unpack = coerce newtype Example = Example String deriving Show main :: IO () main = do print (pack "hello" :: Example) print (unpack (Example "world") :: String) }}} Does this suit your needs? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13592#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler