Use GeneralizedNewtypeDeriving to automatically create associated type families

Here's a simple example:

class C a where
    type T a

instance C Int where
    type T Int = Bool

newtype NT = NT Int
    deriving C

Trac metadata

Trac field	Value
Version	7.6.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture