#10971: ExtendedDefaultRules defaults to [] for Foldable/Traversable -------------------------------------+------------------------------------- Reporter: kanetw | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: 10963 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- From goldfire:
Extend -XExtendedDefaultRules to allow defaulting when one of the classes involved is Foldable or Traversable. (See the current rules ​here.) This will mean, essentially, that there will be two lists of default types, one list at kind * and one at kind * -> *. Both lists should be settable by the user by the default directive. (GHC can figure out which list is being set quite easily.) The default default list for * -> * will be [].
-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10971 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler