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

David Van Horn wrote:
>*
*>* Uh, how do you represent the set of all even numbers, for example?
*>*
*>* 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.
*>*
*
Good example... in fact, I didn't even thought about it when I
implemented this... ahah Funny. Thanks for the counterexample.
I guess the characteristic function approach involves using lambdas to
represent a set... :-/ I am worried with efficiency but I will give it a
try.
>* David
*>* _________________________________________________
*>* For list-related administrative tasks:
*>* http://list.cs.brown.edu/mailman/listinfo/plt-scheme
*