#14042: Data type with type family in return kind spuriously rejected -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Keywords: TypeInType, Resolution: | TypeFamilies Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): There are other places where we don't accept a type-function application; e.g. {{{ type instance F Int = Bool instance C (F Int) where ... }}} And rightly so. This one is, I grant you, less justifiable. But I think it'd be fiddly to support, and the motivation seems weak. After all, data families always have result kind `*` so why not say so? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14042#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler