How to build hana :: tuple_t <T, T, T, ...> a given value of T and the number of elements n

Question

This seems like a pretty simple thing, so I'm looking for a more or less short, built-in, and easy to read solution.
The shortest thing I could imagine is

hana::unfold_left<hana::tuple_tag>( hana::int_c<n>, [] ( auto count ) { return hana::if_( count == hana::int_c<0>, hana::nothing, hana::just( hana::make_pair( count - hana::int_c<1>, hana::type_c<T> ) ) ); } ); 

which is far from being short and readable ...

Answer 1

As pointed out by @jv_ hana::replicate , you can do just that.
The example in the reference documentation provides enough information on how to achieve this:

 // Copyright Louis Dionne 2013-2016 // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) #include <boost/hana/equal.hpp> #include <boost/hana/integral_constant.hpp> #include <boost/hana/optional.hpp> #include <boost/hana/replicate.hpp> #include <boost/hana/tuple.hpp> namespace hana = boost::hana; static_assert(hana::replicate<hana::tuple_tag>('x', hana::size_c<2>) == hana::make_tuple('x', 'x'), ""); // Of course, there can't be more than one element in an `optional`. static_assert(hana::replicate<hana::optional_tag>('x', hana::size_c<2>) == hana::just('x'), ""); int main() { }