Thank you for your answer. Regards, Matthijs On 8/25/16 3:06 AM, Louis Dionne wrote:

Hana does not provide a way to merge two maps out of the box, although that would be very useful. I added a feature request at [1]. For now, you can use `fold_left` with `insert` to insert each element of the

#include #include <string> namespace hana = boost::hana; using namespace hana::literals;

constexpr auto m1 = hana::make_map( hana::make_pair("key1"_s, hana::type_cstd::string), hana::make_pair("key2"_s, hana::type_cstd::string) );

constexpr auto m2 = hana::make_map( hana::make_pair("key3"_s, hana::type_cstd::string), hana::make_pair("key4"_s, hana::type_cstd::string), hana::make_pair("key5"_s, hana::type_cstd::string) );

constexpr auto result = hana::fold_left(m1, m2, hana::insert); constexpr auto expected = hana::make_map( hana::make_pair("key1"_s, hana::type_cstd::string), hana::make_pair("key2"_s, hana::type_cstd::string), hana::make_pair("key3"_s, hana::type_cstd::string), hana::make_pair("key4"_s, hana::type_cstd::string), hana::make_pair("key5"_s, hana::type_cstd::string) );

static_assert(result == expected, "");

int main() { }

Also, while posting on this list is OK, please note that the preferred way to ask Hana-related questions is on StackOverflow with the [boost-hana] tag, as documented at [2]. This allows everybody to benefit from questions and answers, and I am registered to the tag so there's no chance that I miss your question as on this list.

Regards, Louis

[1]: https://github.com/boostorg/hana/issues/299 [2]: http://boostorg.github.io/hana/#tutorial-support

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