Set

import std.stdio;

Set!string s;
s.add("hello");
assert(s.length == 1);
assert(equal(s.iterate, only("hello")));
s.remove("hello");
assert(s.length == 0);
s.remove("hello");
assert(s.length == 0);

s.create(only("hello", "hello", "world"));
assert(s.length == 2);

s.join(set(only("and", "bye")));
assert(s.length == 4);

auto other = set(only("and", "bye", "!"));
auto cross0 = s.intersection(other);
assert("bye" in cross0);
assert("!"  !in cross0);
auto cross1 = other.intersection(s);
assert(cross0.length == cross1.length);
assert("and" in cross0 && "and" in cross1);
assert("bye" in cross0 && "bye" in cross1);

auto nums = set(iota(10));
auto someNums = nums.difference(set(only(1,2,3)));
assert(0 in someNums);
assert(1 !in someNums);

bool f(const Set!string s) {
    return "yes" in s;
}

Set!string ss;
ss.add("yes");
f(ss);
assert("yes" in ss);