diff --git a/source/mijin/types/typedef.hpp b/source/mijin/types/typedef.hpp
new file mode 100644
index 0000000..09cc240
--- /dev/null
+++ b/source/mijin/types/typedef.hpp
@@ -0,0 +1,82 @@
+
+#pragma once
+
+#if !defined(MIJIN_TYPES_TYPEDEF_HPP_INCLUDED)
+#define MIJIN_TYPES_TYPEDEF_HPP_INCLUDED 1
+
+#include <utility>
+
+namespace mijin
+{
+
+//
+// public defines
+//
+
+#define MIJIN_TYPEDEF(name_, base_)                       \
+namespace impl { struct name_ ## _tag; }                  \
+using name_ = mijin::TypeDef<base_, impl::name_ ## _tag>
+
+//
+// public constants
+//
+
+//
+// public types
+//
+
+template<typename TBase, typename TTag>
+class TypeDef
+{
+private:
+    TBase value;
+public:
+    TypeDef() = default;
+    TypeDef(const TypeDef&) = default;
+    TypeDef(TypeDef&&) = default;
+
+    template<typename... TArgs>
+    constexpr TypeDef(TArgs&&... args) : value(std::forward<TArgs>(args)...) {}
+
+    TypeDef& operator=(const TypeDef&) = default;
+    TypeDef& operator=(TypeDef&&) = default;
+
+    template<typename TArg>
+    constexpr TypeDef& operator=(TArg&& arg)
+    {
+        value = std::forward<TArg>(arg);
+        return *this;
+    }
+
+    explicit constexpr operator const TBase&() const noexcept { return value; }
+    explicit constexpr operator TBase&() noexcept { return value; }
+    auto operator<=>(const TypeDef&) const noexcept = default;
+};
+
+template<typename TBase, typename TTag> requires (!std::is_fundamental_v<TBase>)
+class TypeDef<TBase, TTag> : public TBase
+{
+public:
+    TypeDef() = default;
+    TypeDef(const TypeDef&) = default;
+    TypeDef(TypeDef&&) = default;
+    template<typename... TArgs>
+    constexpr TypeDef(TArgs&&... args) : TBase(std::forward<TArgs>(args)...) {}
+
+    TypeDef& operator=(const TypeDef&) = default;
+    TypeDef& operator=(TypeDef&&) = default;
+
+    template<typename TArg>
+    constexpr TypeDef& operator=(TArg&& arg)
+    {
+        TBase::operator=(std::forward<TArg>(arg));
+        return *this;
+    }
+};
+
+//
+// public functions
+//
+
+} // namespace mijin
+#endif // !defined(MIJIN_TYPES_TYPEDEF_HPP_INCLUDED)