closed-classes.md

@@ -16,7 +16,7 @@ class closed ... where
 
 this will mean that even if the class is exported no one may declare more instances for it
 
-## alternate
+## alternate, better proposal
 
 
 specify it in the export list
@@ -25,12 +25,14 @@ specify it in the export list
 module Foo(closed Foo(..)) where
 ```
 
+
+this has the advantage that you can create instances in several modules in a private implementation then export them closed in the public interface. it also fits in nicely with the idea of explicit namespaces in  the [ModuleSystem](module-system) and the readonly modifier in the [ReadonlyConstructors](readonly-constructors) proposal.
+
 ## pro
 
 - compilers based on jhc's class system can take very good advantage of such declarations when optimizing.
 - This sort of thing is often needed when doing phantom type and type class tricks.
 - this is available in helium in order to increase the accuracy of error messages to good effect.
-- syntax is similar to 'class alias' and 'class overlapping' proposals
 
 ## con