#13524: GHC does not preserve order of forall'd vars with TypeApplications -------------------------------------+------------------------------------- Reporter: crockeea | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: | TypeApplications 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 goldfire): Hmm. When the user gives a partial type signature, a whole new code path is used when checking the function. It seems this code path does not respect the order of specified type variables. @niteria's patch likely just exposed the underlying fragility; I don't think investigating that patch will yield any tasty fruit. I'm afraid I'm unable to address this right now, unfortunately. We could advertise this as an infelicity (I'm fairly confident the problem will happen only with a partial type signature). Perhaps even better, we could label variables in partial type signatures as "inferred", meaning that GHC will prevent them from being available for type application. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13524#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler