#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 mpickering): @Richard, it seems to me the crux of the problem is that type instances introduce equalities so they must be interleaved with the other declarations. Data instances are just one place where these extra equalities can be used, another being kind checking for type equalities as in comment:17. Here is the wiki page I started. It is not complete but I am too tired to carry on tonight. Perhaps you could look Alex and fill in some of the details? https://ghc.haskell.org/trac/ghc/wiki/InterleavingTypeInstanceChecking -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12088#comment:24 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler