1 files changed, 31 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/type/is_valid.cpp b/src/boost/libs/hana/example/type/is_valid.cpp
new file mode 100644
index 000000000..a683e78f1
--- /dev/null
+++ b/src/boost/libs/hana/example/type/is_valid.cpp
@@ -0,0 +1,31 @@
+// Copyright Louis Dionne 2013-2017
+// 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/assert.hpp>
+#include <boost/hana/not.hpp>
+#include <boost/hana/type.hpp>
+
+#include <string>
+#include <vector>
+namespace hana = boost::hana;
+
+
+int main() {
+    // Checking for a member
+    struct Person { std::string name; };
+    auto has_name = hana::is_valid([](auto&& p) -> decltype((void)p.name) { });
+
+    Person joe{"Joe"};
+    static_assert(has_name(joe), "");
+    static_assert(!has_name(1), "");
+
+
+    // Checking for a nested type
+    auto has_value_type = hana::is_valid([](auto t) -> hana::type<
+        typename decltype(t)::type::value_type
+    > { });
+
+    static_assert(has_value_type(hana::type_c<std::vector<int>>), "");
+    static_assert(!has_value_type(hana::type_c<Person>), "");
+}