What I mean is: the renaner cannot reject the right set of programs (see comment:8). So the renamer must err on the side of acceptance, and leave
#14131: Difference between newtype and newtype instance -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: RyanGlScott Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: TypeFamilies Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #7938, #9574, | Differential Rev(s): Phab:D3872 #13985 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Replying to [comment:11 simonpj]: the type checker to reject programs where variables appear on the RHS that are not bound on the left. Right, this is exactly what Phab:D3872 is doing at the moment. In particular, it changes `TcTyClsDecls` so that we check for free-floating kind variables (or, as you put it, variables that appear on the RHS that are not bound on the left) when typechecking family instances. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14131#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler