Type-qualified functions?

[Sean Eskapp]

> templates:

> void foo(T)(T, void delegate(T) fn)
> {
> }

> This parameterizes foo based on T, which could be A, const A, or int, or
> whatever works to compile the function.

What if the parameters are more general, for instance the first parameter is
always a Foo, the second is a delegate which takes a Foo.Bar, but they're always
qualified the same way?