is_stateless was a mistake. It is poorly defined and of very limited value. The only place it is used in Boost is in Function, where it's interacting badly with the new operator== functionality.

I'd like to deprecate it in CVS head, or even outright kill it. Any objections?

Sorry to take so long to reply - yes by all means lets deprecate it if it's no longer going to be used within boost. John.