#10499: Constraints should associate over ~ -------------------------------------+------------------------------------- Reporter: joelteon | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Building the smallcheck package fails with this error: {{{ Test/SmallCheck/Property.hs:187:10: Could not deduce (Monad n) arising from the superclasses of an instance declaration from the context: (Monad m, m ~ n) bound by the instance declaration at Test/SmallCheck/Property.hs:187:10-52 Possible fix: add (Monad n) to the context of the instance declaration In the instance declaration for ‘Testable n (Property m)’ }}} Wondering if this is a bug in 7.11's constraint solver or 7.10's, since 7.10 and previous GHCs accept it and 7.11 doesn't. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10499 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler