[plt-scheme] Equivalent of abstract classes?

On Sat, Dec 5, 2009 at 6:24 PM, Todd O'Bryan <toddobryan at gmail.com> wrote:
> Is there the equivalent of Java's abstract classes  (i.e., interfaces
> with some default implementations) in PLT's class system?

That sounds a lot like traits:

http://docs.plt-scheme.org/guide/classes.html#(part._.Traits)
http://docs.plt-scheme.org/reference/trait.html

--Carl