#14352: Higher-rank kind ascription oddities -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 (Type checker) | Keywords: TypeInType | 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: -------------------------------------+------------------------------------- GHC accepts these two definitions: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Proxy f :: forall (x :: forall a. a -> Int). Proxy x f = Proxy g :: forall (x :: forall a. a -> Int). Proxy (x :: forall b. b -> Int) g = Proxy }}} However, it does not accept this one, which (AFAICT) should be equivalent to the two above: {{{#!hs h :: forall x. Proxy (x :: forall b. b -> Int) h = Proxy }}} {{{ GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:13:23: error: • Expected kind ‘forall b. b -> Int’, but ‘x’ has kind ‘k0’ • In the first argument of ‘Proxy’, namely ‘(x :: forall b. b -> Int)’ In the type signature: h :: forall x. Proxy (x :: forall b. b -> Int) | 13 | h :: forall x. Proxy (x :: forall b. b -> Int) | ^ }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14352 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler