#14288: ScopedTypeVariables with nested foralls broken since 8.0.2 -------------------------------------+------------------------------------- Reporter: MikolajKonarski | Owner: RyanGlScott Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: GHC rejects | (amd64) valid program | Test Case: Blocked By: | Blocking: Related Tickets: #14498 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): I had been pushing for this change since I was convinced it was necessary to bring into scope the existentially quantified type variables in pattern synonym type signatures. But the discussion in #14498 has marched in the opposite direction (in particular, see https://ghc.haskell.org/trac/ghc/ticket/14498#comment:16). There, the consensus seems to be that we should //not// bring into scope these existentially quantified variables. In light of this, my original motivation for pursuing this ticket has disappeared, so I think we should go with the plan in comment:5 and document the current behavior. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14288#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler