#9123: Need for higher kinded roles -------------------------------------+------------------------------------- Reporter: simonpj | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Project (more Type of failure: | than a week) None/Unknown | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonpj): I think it'd be better to consider any non-type-variable context as exotic, and reject it. You can always use standalone deriving. The trouble is that it's very easy to get contexts like `(C T)`, which perhaps might be satisfiable at the call site, but not at the `deriving` site, but that is unusual, and the programmer ought to be calling it out explicitly. GHC originally accepted more exotic `deriving` contexts, and moved step by step to the current fairly conservative position. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9123#comment:34 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler