#10116: Closed type families: Warn if it doesn't handle all cases -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 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 rwbarton): This might fall out of the implementation anyways, but a special case to be aware of is non-exhaustiveness in implicit kind variables, such the return kind of a polykinded type family, as arose in #11275: {{{ type family Hm :: k where Hm = Int }}} Despite appearances this type family is not exhaustive: `Hm :: (* -> *)` will not reduce. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10116#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler