1. Do SCC analysis on all declarations except for open type family instances, to give ordered `TyClGroup`s and the set of those instances (in
2. Before checking the `TyClGroup`s, put all equalities arising from the open type family instances into the environment (assume for now that
#12088: Type/data family instances in kind checking -------------------------------------+------------------------------------- Reporter: alexvieth | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: #11348, #12239 | Differential Rev(s): Phab:D2272 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Replying to [comment:16 alexvieth]: source file order). they're well-kinded).
3. Check the `TyClGroup`s in order as usual. 4. Check the open type family instances (verifying or falsifying the assumption in 2).
Maybe this is nonsense. Would it be possible to make and use a coercion axiom without kind checking the lhs and rhs types?
I'm not sure I understand. Currently, kind-checking an instance and desugaring it are all done at the same time, so step (2) is hard to implement. Let's say we get around that barrier, though. This would then put ill-kinded equalities into the context. I think it would be awfully hard to avoid getting GHC to loop or do other silly things with a bad context. Perhaps you could squeeze this through, but I'm very skeptical. Or am I misunderstanding something? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12088#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler