#16140: Cannot create type synonym for quantified constraint without ImpredicativeTypes -------------------------------------+------------------------------------- Reporter: Ashley Yakeley | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: | Keywords: | QuantifiedConstraints, | ImpredicativeTypes Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): The good news is that #16059 has been fixed. The downside is that I just discovered that the only reason that I managed to get the program in this ticket to work (after implementing the suggestion in comment:3) is //because// of #16059! That is to say, when I try implementing comment:3 now, GHC's improved type validity-checker now rejects the program in this ticket. Bummer. It looks like calling `check_pred_ty` isn't enough—there must be something deeper that needs to be changed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16140#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler