Comment re Trac #1220

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index d414c6f..774bbe9 100644 (file)
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -222,6 +222,9 @@ And then translate it to:
        
 Note [Newtype deriving superclasses]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+(See also Trac #1220 for an interesting exchange on newtype
+deriving and superclasses.)
+
 The 'tys' here come from the partial application in the deriving
 clause. The last arg is the new instance type.