#13154: Standalone-derived anyclass instances aren't as permissive as empty instances -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.1 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4337, Wiki Page: | Phab:D4370 -------------------------------------+------------------------------------- Comment (by RyanGlScott): No. There is a smattering of things that still aren't supported, which include (but may not be limited to): * Instances for bare type variables: {{{#!hs instance Foo a -- Works deriving anyclass instance Foo a -- Doesn't work }}} * Instances for type-level literals: {{{#!hs instance Bar 1 -- Works deriving anyclass instance Bar 2 -- Doesn't work }}} * Empty instances: {{{#!hs instance Baz -- Works deriving instance Baz -- Doesn't work }}} I have an idea of how to fix these, but haven't had the time to try it out yet. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13154#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler