GHC confused about type synonym kind with QuantifiedConstraints
{-# LANGUAGE KindSignatures, RankNTypes, ConstraintKinds, QuantifiedConstraints #-}
module Bug where
import Data.Constraint
type E (c :: * -> Constraint) = forall (a :: *). Eq a => c aBug.hs:5:58: error:
• Expected a type, but ‘c a’ has kind ‘Constraint’
• In the type ‘forall (a :: *). Eq a => c a’
In the type declaration for ‘E’
|
5 | type E (c :: * -> Constraint) = forall (a :: *). Eq a => c a
| ^^^Note that GHC accepts the program when the Eq a constraint is removed.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.6.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |