chickadee » srfi-113 » set-union

set-union set1 set2 ...procedure
set-intersection set1 set2 ...procedure
set-difference set1 set2 ...procedure
set-xor set1 set2procedure

Return a newly allocated set that is the union, intersection, asymmetric difference, or symmetric difference of the sets. Asymmetric difference is extended to more than two sets by taking the difference between the first set and the union of the others. Symmetric difference is not extended beyond two sets. Elements in the result set are drawn from the first set in which they appear.