clopenset where being empty isn't quite enough

Here it is: http://code.google.com/p/ductilesharp/

I have created the "Mono C# extensibility project" with the intention of making it straightforward to write custom add-ins for the Mono C# compiler.

Here's a link: http://github.com/rcook/mono-extensibility/

I'm hoping to contribute to the DuctileJ project at some point over the next few weeks.