diff --git a/example/hanoi/main.cpp b/example/hanoi/main.cpp
new file mode 100644
index 00000000..b60ea09a
--- /dev/null
+++ b/example/hanoi/main.cpp
@@ -0,0 +1,48 @@
+/*=============================================================================
+  Copyright (c) 2011-2013 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+
+#include <cstddef>
+#include <sprout/array.hpp>
+#include <sprout/tuple/tuple.hpp>
+#include <sprout/operation/push_back.hpp>
+#include <sprout/operation/append_back.hpp>
+#include <sprout/integer/static_pow.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+
+//
+// hanoi
+//
+template<
+	std::size_t N, typename Id,
+	typename sprout::enabler_if<(N == 0)>::type = sprout::enabler
+>
+SPROUT_CONSTEXPR sprout::array<sprout::tuple<Id, Id, std::size_t>, 0>
+hanoi(Id, Id, Id) {
+	return sprout::array<sprout::tuple<Id, Id, std::size_t>, 0>{{}};
+}
+template<
+	std::size_t N, typename Id,
+	typename sprout::enabler_if<(N != 0)>::type = sprout::enabler
+>
+SPROUT_CONSTEXPR sprout::array<sprout::tuple<Id, Id, std::size_t>, sprout::static_pow2m1<std::size_t, N>::value>
+hanoi(Id a, Id b, Id c) {
+	typedef sprout::tuple<Id, Id, std::size_t> type;
+	return sprout::append_back(
+		sprout::push_back(hanoi<N - 1>(a, c, b), type(a, b, N)),
+		hanoi<N - 1>(c, b, a)
+		);
+}
+
+#include <iostream>
+
+int main() {
+	constexpr auto answer = hanoi<8>('a', 'b', 'c');
+	for (auto const& e : answer) {
+		std::cout << "disk " << sprout::get<2>(e) << ": " << sprout::get<0>(e) << " -> " << sprout::get<1>(e) << std::endl;
+	}
+}
diff --git a/sprout/integer.hpp b/sprout/integer.hpp
new file mode 100644
index 00000000..190530e0
--- /dev/null
+++ b/sprout/integer.hpp
@@ -0,0 +1,15 @@
+/*=============================================================================
+  Copyright (c) 2011-2013 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_INTEGER_HPP
+#define SPROUT_INTEGER_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/integer/integer_digits.hpp>
+#include <sprout/integer/static_pow.hpp>
+
+#endif	// #ifndef SPROUT_INTEGER_HPP
diff --git a/sprout/integer/static_pow.hpp b/sprout/integer/static_pow.hpp
new file mode 100644
index 00000000..e92f737c
--- /dev/null
+++ b/sprout/integer/static_pow.hpp
@@ -0,0 +1,76 @@
+/*=============================================================================
+  Copyright (c) 2011-2013 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_INTEGER_STATIC_POW_HPP
+#define SPROUT_INTEGER_STATIC_POW_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+
+namespace sprout {
+	//
+	// static_pow2
+	//
+	template<typename T, T X>
+	struct static_pow2
+		: public std::integral_constant<T, (1 << X)>
+	{};
+
+	namespace detail {
+		template<typename T, T X, bool IsZero = (X == 0)>
+		struct static_pow2m1;
+		template<typename T, T X>
+		struct static_pow2m1<T, X, true>
+			: public std::integral_constant<T, 1>
+		{};
+		template<typename T, T X>
+		struct static_pow2m1<T, X, false>
+			: public std::integral_constant<T, ((((T(1) << (X - 1)) - 1) << 1) + 1)>
+		{};
+	}	// namespace detail
+	//
+	// static_pow2m1
+	//
+	template<typename T, T X>
+	struct static_pow2m1
+		: public sprout::detail::static_pow2m1<T, X>
+	{};
+
+	namespace detail {
+		template<typename T, T X, T Y, int K = (Y < 3 ? int(Y) : 3), bool IsOdd = (Y % 2 != 0)>
+		struct static_pow;
+		template<typename T, T X, T Y>
+		struct static_pow<T, X, Y, 0, false>
+			: public std::integral_constant<T, 1>
+		{};
+		template<typename T, T X, T Y>
+		struct static_pow<T, X, Y, 1, true>
+			: public std::integral_constant<T, X>
+		{};
+		template<typename T, T X, T Y>
+		struct static_pow<T, X, Y, 2, false>
+			: public std::integral_constant<T, X * X>
+		{};
+		template<typename T, T X, T Y, int K>
+		struct static_pow<T, X, Y, K, false>
+			: public sprout::detail::static_pow<T, sprout::detail::static_pow<T, X, Y / 2>::value, 2>
+		{};
+		template<typename T, T X, T Y, int K>
+		struct static_pow<T, X, Y, K, true>
+			: public std::integral_constant<T, X * sprout::detail::static_pow<T, X, Y - 1>::value>
+		{};
+	}	// namespace detail
+	//
+	// static_pow
+	//
+	template<typename T, T X, T Y>
+	struct static_pow
+		: public sprout::detail::static_pow<T, X, Y>
+	{};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_INTEGER_STATIC_POW_HPP
diff --git a/testspr/header_all.hpp b/testspr/header_all.hpp
index d652fc4f..ae125a08 100644
--- a/testspr/header_all.hpp
+++ b/testspr/header_all.hpp
@@ -40,7 +40,7 @@
 #include <sprout/generator.hpp>
 #include <sprout/index_tuple.hpp>
 #include <sprout/io.hpp>
-#include <sprout/integer/integer_digits.hpp>
+#include <sprout/integer.hpp>
 #include <sprout/iterator.hpp>
 #include <sprout/limits.hpp>
 #include <sprout/logic.hpp>
diff --git a/tools/testspr/test.py b/tools/testspr/test.py
index 52a8903f..44383772 100644
--- a/tools/testspr/test.py
+++ b/tools/testspr/test.py
@@ -30,6 +30,9 @@ def main():
 	parser.add_option('--max_procs', type='int', default=0)
 	(opts, args) = parser.parse_args()
 
+	std_options = eval(opts.serialized_std_options)
+	version_specific_options = eval(opts.serialized_version_specific_options)
+
 	def format_command(name, version, root):
 		base = "%s-%s" % (name, version) if version != "." else name
 		bin = "%s/test.%s.out" % (opts.stagedir, base.replace('.', ''))
@@ -37,13 +40,11 @@ def main():
 		execute_log = "%s/test.%s.execute.log" % (opts.stagedir, base.replace('.', ''))
 		compiler = "%s/%s/bin/%s++" % (root, base, name.rstrip('c')) if version != "." else "%s++" % name.rstrip('c')
 		return "%s -o %s" \
-			" %s %s" \
-			" %s" \
+			" %s %s %s" \
 			" %s > %s 2>&1" \
 			" && %s > %s 2>&1" \
 			% (compiler, bin,
-				eval(opts.serialized_std_options).get(base, ''), opts.compile_options,
-				eval(opts.serialized_version_specific_options).get(base, ''),
+				std_options.get(base, ''), opts.compile_options, version_specific_options.get(base, ''),
 				opts.test_cpp, compile_log,
 				bin, execute_log
 				)