2_lambda_notworking.cpp

// Copyright (c) 2015-2016 Vittorio Romeo
// License: Academic Free License ("AFL") v. 3.0
// AFL License page: http://opensource.org/licenses/AFL-3.0
// http://vittorioromeo.info | vittorio.romeo@outlook.com

// #define VR_USE_BOOST_VARIANT

#include <iostream>
#include <vector>
#include <boost/hana.hpp>
#include "variant_aliases.hpp"

namespace impl
{
    struct vnum_wrapper;

    using varr = std::vector<vnum_wrapper>;
    using vnum = vr::variant<int, float, double, varr>;

    struct vnum_wrapper : public vnum
    {
        using vnum::vnum;
    };
}

using vnum = impl::vnum_wrapper;
using impl::varr;

template <typename... TFs>
auto make_visitor(TFs&&... fs)
{
    return boost::hana::overload(FWD(fs)...);
}

int main()
{
    // clang-format off
    auto vnp = make_visitor
    (
        [](int x)    { std::cout << x << "i\n"; },
        [](float x)  { std::cout << x << "f\n"; },
        [](double x) { std::cout << x << "d\n"; },
      
        [&](const varr& arr)
        {
            for(const auto& x : arr)
            {
                vr::visit(vnp, x);
            }
        }
    );
    // clang-format on

    vnum v0{0};
    vr::visit(vnp, v0);

    v0 = 5.f;
    vr::visit(vnp, v0);

    v0 = 33.51;
    vr::visit(vnp, v0);

    v0 = varr{vnum{1}, vnum{2.0}, vnum{3.f}};
    vr::visit(vnp, v0);

    v0 = varr{vnum{5}, varr{vnum{7}, vnum{8.0}, vnum{9.}}, vnum{4.f}};
    vr::visit(vnp, v0);
}