Can't resolve levity polymorphic superclass
This works
{-# Language PolyKinds, TypeInType #-}
import GHC.Exts (TYPE, RuntimeRep)
class A (a :: TYPE rep)
class A a => B (a :: TYPE rep)
instance A b => A (a -> (b :: TYPE rep))
instance B b => B (a -> b)
but the moment you add (b :: TYPE rep
) to the last line it stops working
-- t3I7.hs:9:10-40: error: …
-- • Could not deduce (A b)
-- arising from the superclasses of an instance declaration
-- from the context: B b
-- bound by the instance declaration at /tmp/t3I7.hs:9:10-40
-- • In the instance declaration for ‘B (a -> b)’
-- Compilation failed.
{-# Language PolyKinds, TypeInType #-}
import GHC.Exts (TYPE, RuntimeRep)
class A (a :: TYPE rep)
class A a => B (a :: TYPE rep)
instance A b => A (a -> (b :: TYPE rep))
instance B b => B (a -> (b :: TYPE rep))
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |