1 files changed, 35 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/extend.cpp b/src/boost/libs/hana/example/extend.cpp
new file mode 100644
index 00000000..9d5351b1
--- /dev/null
+++ b/src/boost/libs/hana/example/extend.cpp
@@ -0,0 +1,35 @@
+// 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/eval.hpp>
+#include <boost/hana/extend.hpp>
+#include <boost/hana/extract.hpp>
+#include <boost/hana/lazy.hpp>
+
+#include <functional>
+#include <istream>
+#include <sstream>
+namespace hana = boost::hana;
+
+
+template <typename T>
+T read_one(std::istream& s) {
+    T value;
+    s >> value;
+    return value;
+}
+
+int main() {
+    std::stringstream s;
+    s << "1 2 3";
+
+    auto from_stream = hana::extend(hana::make_lazy(read_one<int>)(std::ref(s)), [](auto i) {
+        return hana::eval(i) + 1;
+    });
+
+    BOOST_HANA_RUNTIME_CHECK(hana::extract(from_stream) == 2);
+    BOOST_HANA_RUNTIME_CHECK(hana::extract(from_stream) == 3);
+    BOOST_HANA_RUNTIME_CHECK(hana::extract(from_stream) == 4);
+}