#14579: GeneralizedNewtypeDeriving produces ambiguously-kinded code -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.10.1 Component: Compiler (Type | Version: 8.2.2 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | deriving/should_compile/T14579{a} Blocked By: 12045 | Blocking: Related Tickets: | Differential Rev(s): Phab:D4264, Wiki Page: | Phab:D5229 -------------------------------------+------------------------------------- Comment (by simonpj):
I was originally hopeful that we could avoid generating any explicit kind signatures and exclusively use visible kind application.
Yes I agree with your analysis. Visible kind application (VKA) can only be used for Specified arguments, and user-defined types can have Inferred arguments. So yes, if there are no Inferred ones (a common case) you can use VKA; but not if not. Annoying! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14579#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler