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 a
Bug.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 |