merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/extra/guile/scm/detail/function_args.hpp

@@ -0,0 +1,21 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#pragma once
+
+#include <scm/detail/pack.hpp>
+#include <boost/callable_traits/args.hpp>
+
+namespace scm {
+namespace detail {
+
+template <typename Fn>
+using function_args_t = boost::callable_traits::args_t<Fn, pack>;
+
+} // namespace detail
+} // namespace scm