heckell is a programming language for set theory.
$ make
$ ./heckell < (YOURFILE).hck
let S1 : int set;
S1 = { 1, 2, 2 };
print("Creating set S1 = {1, 2, 2}");
let S2 : int set;
S2 = { 2, 8, 9 };
print("Creating set S2 = {2, 8, 9}");
let S3 : int set;
S3 = S1 + S2;
print("S1 + S2 ==> \(S3)");
let S4 : int set;
S4 = S2 - S1;
print("S2 - S1 ==> \(S4)");