#12679: Permit abstract data types in signatures that don't have kind * -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 8.1 checker) | Resolution: | Keywords: backpack 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 goldfire): I don't think this is #11715 but is instead related to the commentary in #12680, where there seems to be some confusion about `data` vs `type` in signatures. See comment:10:ticket:12680 and comment:11:ticket:12680. If `data` can be implemented by a type synonym (something I dislike, to be honest), then `class` should be too. Can you use `class` instead of `data` in your example? That would seem to meet your needs. After all, `class` is essentially the same as `data` but with a different result kind. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12679#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler