#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 simonpj):
Ah, I think I managed to confuse you
I am indeed terribly confused. I can now just about see what you are doing. * The `hsib_vars` wrapped around the `HsTyPats` includes (via the renamer) the variables mentioned in the RHS. You arrange that `tc_fam_ty_pats` returns them to its caller. * Now in `tcFamTyPats` you can take that set of variables, and subtract from it those bound on the LHS (gotten from the free vars of the typechecked pates). Result is the ones on the RHS but not LHS. Ugh! I bet that all this will look different, and much more perspicous, once we've done the refactoring in comment:9. As you suggest, let's do that first. Yell if you need any help -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14131#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler