#9151: Recursive default associated types don't kind-generalize properly -------------------------------------+------------------------------------ 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): Replying to [comment:4 archblob]:
That second example is somewhat alarming -- the associated type family does not mention > any class parameters. I'm surprised that's accepted!
@goldfire, wasn't this introduced in #7939 ?
Perhaps, but if so, it was certainly not intentional. That work should make `b` poly-kinded, but it shouldn't necessarily make `F` accepted. I'm actually surprised that kind-checking strategies have much to do with this bug, but I haven't looked into it. When you change strategies, how does that affect other programs? As outlined in the very long comment explaining them and in #7939, kind-checking strategies are fiddly and subtle, a dangerous combination. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9151#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler