#10447: DeriveFoldable rejects instances with constraints in last argument of data type -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: #8678 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by dolio): I'm not asking if GHC would derive the instance I specified. I'm asking whether it's an okay `Foldable` instance based on the same reasoning as for: {{{ data Bar a where Bar :: (a ~ Int) -> Int -> Bar a }}} and the like. "Can we automatically do this," is not the only relevant question. "Should we do this and why," also matters. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10447#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler