#10586: GHC 7.10.1 panic due to wildcard in data family instance -------------------------------------+------------------------------------- Reporter: WrenThornton | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #3699 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by thomasw): Replying to [comment:7 simonpj]:
I'm actually thinking about adding support for wild cards in data/type instances. I would just replace them with fresh meta variables. This would also address #3699. I don't think named wild cards or extra-constraints wild cards make sense here. What do you think?
Yes, I agree. Do not use a ''meta'' variable. These are really ''skolems'', just like the named type variables in an ordinary declaration, just anonymous ones.
Given the freshly generated `Name` of an anonymous wild card, which function should I use to create a skolem? `newSigTyVar :: Name -> Kind -> TcM TcTyVar` in TcMType using `newMetaKindVar :: TcM TcKind` as kind? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10586#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler