let set = {
	mt = {
		__type = "set"
		__tostring = fn (self) {
			return raw_get(self, "values")
		}
		__get = fn (self, v) {
			return raw_get(self, "values"):contains(v)
		}
	}
}
fn set.new(values) {
	return setmeta({
		values = values,
	}, set.mt)
}
fn set.insert(self, v) {
	let values = raw_get(self, "values")
	if !values:contains(v) {
		values:push(v)
	}
}
fn set.remove(self, rv) {
	let values = raw_get(self, "values")
	let pos = null
	for i in range(raw_get(self, "values"):len()) {
		if values[i] == rv {
			pos = i
			break
		}
	}
	if pos {
		values:pop(pos)
	}
}

let s = set.new([1, 2, 3])
print(type(s)) # set
print(s) # [1, 2, 3]
set.insert(s, 4)
print("inserted 4:", s) # [1, 2, 3]
set.remove(s, 2)
print("removed 2:", s) # [1, 2, 3]
print("s[4] =", s[4]) # true
print("s[2] =", s[2]) # false