#8827: Inferring Safe mode with GeneralizedNewtypeDeriving is wrong -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #8226, #8745 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by oerjan): My hunch about `nominal` default is that it would be annoying in the same way that authors forgetting to provide a useful type class for a type is annoying, but worse because a user of the package ''cannot'' afterwards declare an orphan `Coercible` instance, even if they need it. You could write an explicit coercion function, or use `unsafeCoerce`, but if you were an intermediate package writer declaring a wrapping type, you couldn't then provide `Coercible` for the users of ''your'' type. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8827#comment:44 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler