Need more kind inference in associated type instances
When I say
{-# LANGUAGE DataKinds, PolyKinds, TypeFamilies #-}
module Bug where
import Data.Proxy
class kproxy ~ 'KProxy => C (kproxy :: KProxy k) where
type F (a :: k)
instance C ('KProxy :: KProxy Bool) where
type F a = IntI get
Type indexes must match class instance head
Found ‘k’ but expected ‘Bool’
In the type instance declaration for ‘F’
In the instance declaration for ‘C (KProxy :: KProxy Bool)’But the kind of a should really be known to be Bool.
This ticket is broken out from ticket:9063#comment:82569, which was evidently not addressed when fixing that ticket.
Patch coming soon.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.2 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |