Kind variable problem when declaring associated type family
The following code fails to compile:
{-# LANGUAGE PolyKinds, TypeFamilies #-}
class Foo a where
type Bar a
type Bar a = Int
The error I get is
Type indexes must match class instance head
Found `k' but expected `k'
In the type synonym instance default declaration for `Bar'
In the class declaration for `Foo'
When I remove -XPolyKinds
, the code compiles without a hiccup.
This was tested on 7.5.2012.0710
Trac metadata
Trac field | Value |
---|---|
Version | 7.5 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |