Returns the first element of a pair.Note that if the Product actually stores the elements it contains, hana::first is required to return a lvalue reference, a lvalue reference to const or a rvalue reference to the first element, where the type of reference must match that of the pair passed to first. If the Product does not store the elements it contains (i.e. it generates them on demand), this requirement is dropped. More...
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)
