DouKaku?

Iterator::each_pair: method fiber {
    prev: null;
    this { prev = it; break; }
    this {
        yield prev, it;
        prev = it;
    }
}

diff: fun(iter) {
    return iter.each_pair.map(|a,b| b - a);
}

diff([3, 1, 4, 1, 5, 9, 2, 6, 5].each).to_a.p;


// 無限列のテスト
random_generator: fiber {
    while (true) {
        yield math::ceil(math::random_range(1, 10));
    }
}
diff(random_generator).take(20).to_a.p;