On 06/09/2015 11:00 AM, Louis Dionne wrote: [snip]
Indeed, you are using a Map when what you really want is a Tuple, since your keys are integers. Here's the version I would have written:
#include <boost/hana/integral_constant.hpp> #include <boost/hana/range.hpp> #include <boost/hana/tuple.hpp> using namespace boost::hana;
static constexpr int map_size = 100;
void run() { constexpr auto hana_range = range(int_<0>, int_<map_size>); auto hana_tuple = unpack(hana_range, [](auto ...n) { return tuple_t<std::array<char, decltype(n)::value>...>; });
auto Array = hana_tuple[int_<69>];
// instantiate the array constexpr decltype(Array)::type arr = {{0}}; static_assert(sizeof(arr) == 69, ""); }
However, I can easily imagine another example where you actually need the functionality of a Map. See below for performance comments.
[snip] Why couldn't map be implemented as a tuple, as shown here: https://gist.github.com/cppljevans/8e545e8d83946cd74311 Wouldn't that eliminate the difference in performance between map and tuple? -regards, Larry