Does Common Lisp have a something like java's

Question

I need something like this, a collection of elements which contains no duplicates of any element. Does Common Lisp, specifically SBCL, have any thing like this?

Answer 1

Yes, it has sets. See this section on "Sets" from Practical Common Lisp.

Basically, you can create a set with pushnew and adjoin, query it with member, member-if and member-if-not, and combine it with other sets with functions like intersection, union, set-difference, set-exclusive-or and subsetp.

Answer 2

Not that I'm aware of, but you can use hash tables for something quite similar.