#11473: Levity polymorphism checks are inadequate -------------------------------------+------------------------------------- Reporter: simonpj | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.10.3 Resolution: | Keywords: | LevityPolymorphism, TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by rwbarton): What happens with let-bound variables of polymorphic representation? Surely we can't allow this: {{{ {-# LANGUAGE TypeInType, ScopedTypeVariables #-} import GHC.Types app :: forall (l :: Levity) (a :: *) (b :: TYPE l). (a -> b) -> a -> b app f x = let y :: b y = undefined in f x }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11473#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler