История изменений

#include <iostream>
#include <functional>
#include <vector>

template <typename T>
struct stream {
    T first;
    std::function<stream()> rest;
};

template <typename T>
std::vector<T> take(std::size_t n, stream<T> stream)
{
    std::vector<T> result;
    for (; n > 0; --n, stream = stream.rest())
        result.push_back(stream.first);
    return result;
}

stream<int> f(int a, int b)
{
    return { a, [=]() { return f(b, a); } };
}

int main()
{
    auto xs = take(10, f(1, 2));

    for (auto &x : xs)
        std::cout << x << ' ';
    std::cout << std::endl;
}

/*
total heap usage: 16 allocs, 16 frees, 212 bytes allocated
 */

#include <iostream>
#include <functional>
#include <vector>

template <typename T>
struct stream {
    T first;
    std::function<stream()> rest;
};

template <typename T>
std::vector<T> take(std::size_t n, stream<T> stream)
{
    std::vector<T> result;
    for (std::size_t i = 0; i < n; ++i, stream = stream.rest())
        result.push_back(stream.first);
    return result;
}

stream<int> f(int a, int b)
{
    return { a, [=]() { return f(b, a); } };
}

int main()
{
    auto xs = take(10, f(1, 2));

    for (auto &x : xs)
        std::cout << x << ' ';
    std::cout << std::endl;
}

/*
total heap usage: 16 allocs, 16 frees, 212 bytes allocated
 */