#9063: Default associated type instances are too general -------------------------------------+------------------------------------ Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by goldfire): It might help to note ''why'' I'm pushing this. I'm working on expanding the promotion algorithm in the `singletons` package to include classes and instances. I want to promote method definitions to associated type family instances. Currently, something like this is peachy: {{{ instance Eq () where _ == _ = True }}} However, with the current treatment of associated type instances as discussed here, the promoted version of this (in my "instance example" above) does not work without explicit kind annotations. My implementation currently has to store method types, do a lookup on method definitions, and then do a type substitution to produce the needed kind annotations. This isn't terribly hard, really, but it just seems unnecessary. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9063#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler