#15793: Type family doesn't reduce with visible kind application -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: | TypeApplications Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * status: closed => new * resolution: invalid => Comment: But surely we should reject {{{ F2 @a = Maybe a }}} on the grounds that, well, `F2` has arity 0, so you can't supply an `@ty` arg on the left?
We don't yet have the syntax to declare a type family whose argument is both invisible and non-dependent.
Is another way to say this that the final argument of a type family must be `Required`; it cannot be `Specified`? What about `Inferred`? I think that is possible, isn't it? We should document this somehow in the user manual. Re-opening for these reasons. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15793#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler