1 files changed, 36 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/tutorial/constant_side_effects.cpp b/src/boost/libs/hana/example/tutorial/constant_side_effects.cpp
new file mode 100644
index 000000000..ea81ec08e
--- /dev/null
+++ b/src/boost/libs/hana/example/tutorial/constant_side_effects.cpp
@@ -0,0 +1,36 @@
+// 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/bool.hpp>
+
+#include <iostream>
+namespace hana = boost::hana;
+
+
+namespace pure {
+//! [pure]
+template <typename X>
+auto identity(X x) { return x; }
+
+auto x = identity(hana::bool_c<true>);
+static_assert(hana::value(x), "");
+//! [pure]
+}
+
+namespace impure {
+//! [impure_identity]
+template <typename X>
+auto identity(X x) {
+    std::cout << "Good luck in evaluating this at compile-time!";
+    return x;
+}
+//! [impure_identity]
+
+//! [impure]
+auto x = identity(hana::bool_c<true>);
+static_assert(hana::value(x), "");
+//! [impure]
+}
+
+int main() { }