#11451: Inconsistent warnings for unused binders -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Lemming): I think that if a type variable is mentioned in an instance head this should count as usage. Then the according type patterns in associated types should be literally equal and should not get a warning. Thus I go with your second thought. Sure, this is somehow inconsistent with the value level, however, warning about unused type variables in this cases means I have to rewrite lots of code, even Haskell 98 code, to get rid of warnings and I guess, that `instance C (Maybe _)` is not even valid Haskell 98. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11451#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler