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hana/example/integer_list/unfoldl.cpp
2014-07-24 13:24:45 -04:00

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751 B
C++

/*
@copyright Louis Dionne 2014
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/detail/constexpr.hpp>
#include <boost/hana/detail/static_assert.hpp>
#include <boost/hana/integer_list.hpp>
#include <boost/hana/integral.hpp>
#include <boost/hana/maybe.hpp>
#include <boost/hana/pair/instance.hpp>
using namespace boost::hana;
int main() {
//! [main]
BOOST_HANA_CONSTEXPR_LAMBDA auto f = [](auto x) {
return if_(x == int_<0>, nothing, just(pair(x - int_<1>, x)));
};
BOOST_HANA_STATIC_ASSERT(
unfoldl<IntegerList>(f, int_<10>) == integer_list<int, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10>
);
//! [main]
}