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diff --git a/boost/hana/count.hpp b/boost/hana/count.hpp
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+/*!
+@file
+Defines `boost::hana::count`.
+
+@copyright Louis Dionne 2013-2016
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_COUNT_HPP
+#define BOOST_HANA_COUNT_HPP
+
+#include <boost/hana/fwd/count.hpp>
+
+#include <boost/hana/concept/foldable.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/count_if.hpp>
+#include <boost/hana/equal.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! @cond
+    template <typename Xs, typename Value>
+    constexpr auto count_t::operator()(Xs&& xs, Value&& value) const {
+        using S = typename hana::tag_of<Xs>::type;
+        using Count = BOOST_HANA_DISPATCH_IF(count_impl<S>,
+            hana::Foldable<S>::value
+        );
+
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::Foldable<S>::value,
+        "hana::count(xs, value) requires 'xs' to be Foldable");
+    #endif
+
+        return Count::apply(static_cast<Xs&&>(xs), static_cast<Value&&>(value));
+    }
+    //! @endcond
+
+    template <typename T, bool condition>
+    struct count_impl<T, when<condition>> : default_ {
+        template <typename Xs, typename Value>
+        static constexpr auto apply(Xs&& xs, Value&& value) {
+            return hana::count_if(static_cast<Xs&&>(xs),
+                hana::equal.to(static_cast<Value&&>(value)));
+        }
+    };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_COUNT_HPP