easylocal::writable_solution
A Solution that can be written to a stream, given its Input: by a member solution.write(input, out), by a free write_solution(input, solution, out) found by ADL, or by operator<<, in this order.
Synopsis
Declared in <easylocal/app/io.hpp>
template<
class Input,
class Solution>
concept writable_solution = detail::io::has_member_solution_write<Input, Solution>
|| detail::io::adl::has_write_solution<Input, Solution>
|| detail::io::ostream_insertable<Solution>;