#15147: Type checker plugin receives Wanteds that are not completely unflattened -------------------------------------+------------------------------------- Reporter: nfrisby | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.4.1 checker) | Keywords: Resolution: | TypeCheckerPlugins Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by nfrisby): My plugin is responsible for reducing some type families. Receiving flattened Wanteds appeals to me because all of the tyfam applications (except those under forall? hmmm) would be FunEq constraints, so I wouldn't have to seek them out in the types. So perhaps if there were a separate mechanism for the plugin to declare a custom "reducer" for a type family, that might eliminate my interest in flattened Wanteds. Another related quality of life improvement would be easier access to the unflattening substitution, e.g. without having to manually assemble the FunEq constraints. I'm not sure yet, but I think I'll eventually want to only unflatten certain "relevant" type families (and maybe other applications containing applications of those type families). (This is for givens too, not just Wanteds.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15147#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler