Skip to content
GitLab
Projects Groups Snippets
  • /
  • Help
    • Help
    • Support
    • Community forum
    • Submit feedback
  • Sign in / Register
  • GHC GHC
  • Project information
    • Project information
    • Activity
    • Labels
    • Members
  • Repository
    • Repository
    • Files
    • Commits
    • Branches
    • Tags
    • Contributors
    • Graph
    • Compare
    • Locked Files
  • Issues 5,259
    • Issues 5,259
    • List
    • Boards
    • Service Desk
    • Milestones
    • Iterations
  • Merge requests 564
    • Merge requests 564
  • CI/CD
    • CI/CD
    • Pipelines
    • Jobs
    • Schedules
    • Test Cases
  • Deployments
    • Deployments
    • Releases
  • Analytics
    • Analytics
    • Value stream
    • CI/CD
    • Code review
    • Insights
    • Issue
    • Repository
  • Wiki
    • Wiki
  • Snippets
    • Snippets
  • Activity
  • Graph
  • Create a new issue
  • Jobs
  • Commits
  • Issue Boards
Collapse sidebar
  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
  • Issues
  • #14352
Closed
Open
Issue created Oct 14, 2017 by Ryan Scott@RyanGlScottMaintainer

Higher-rank kind ascription oddities

GHC accepts these two definitions:

{-# 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:

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)
   |                       ^
Trac metadata
Trac field Value
Version 8.2.1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information
Assignee
Assign to
Time tracking