[plt-scheme] Is there a set data-type?

On Fri, Feb 5, 2010 at 9:47 AM, David Van Horn <dvanhorn at ccs.neu.edu> wrote:
> This is an exercise we give our first semester undergraduates here at
> Northeastern.  I'll give you a hint: you don't need lists or hash tables, go
> back to the mathematical foundations and think characteristic functions.
>
> Now you do union, intersection, setminus, etc.

Can you make it as efficient as hash-tables in the case that the set is finite?

Robby