diff --git a/COPYING b/COPYING
new file mode 100644
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--- /dev/null
+++ b/COPYING
@@ -0,0 +1,121 @@
+Creative Commons Legal Code
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diff --git a/optional.hpp b/optional.hpp
new file mode 100644
index 0000000..12a128f
--- /dev/null
+++ b/optional.hpp
@@ -0,0 +1,304 @@
+///
+// optional - An implementation of std::optional with extensions
+// Written in 2017 by Simon Brand (@TartanLlama)
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to the
+// public domain worldwide. This software is distributed without any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+///
+
+#include <type_traits>
+#include "tl/type_traits.hpp"
+
+namespace tl {
+  // [optional.optional], class template optional
+  template <class T>
+  class optional;
+
+  // [optional.nullopt], no-value state indicator
+  struct nullopt_t{};
+  inline constexpr nullopt_t nullopt;
+
+  // [optional.bad.access], class bad_­optional_­access
+    class bad_optional_access : public std::exception {
+        bad_optional_access() = default;
+        const char* what() const {
+            return "Optional has no value";
+        }
+    };
+
+  // [optional.relops], relational operators
+  template <class T, class U>
+  inline constexpr bool operator==(const optional<T>& lhs, const optional<U>& rhs) {
+      if (lhs.has_value() != rhs.has_value())
+          return false;
+      if (lhs.has_value())
+          return true;
+
+      return lhs.value() == rhs.value();
+  }
+  template <class T, class U>
+  inline constexpr bool operator!=(const optional<T>& lhs, const optional<U>& rhs) {
+      if (lhs.has_value() != rhs.has_value())
+          return true;
+      if (lhs.has_value())
+          return false;
+
+      return lhs.value() != rhs.value();
+  }
+  template <class T, class U>
+  inline constexpr bool operator<(const optional<T>& lhs, const optional<U>& rhs) {
+      if (!rhs.has_value())
+          return false;
+      if (!lhs.has_value())
+          return true;
+
+      return lhs.value() < rhs.value();
+  }
+  template <class T, class U>
+  inline constexpr bool operator>(const optional<T>& lhs, const optional<U>& rhs) {
+      if (!lhs.has_value())
+          return false;
+      if (!rhs.has_value())
+          return true;
+
+      return lhs.value() > rhs.value();
+  }
+  template <class T, class U>
+  inline constexpr bool operator<=(const optional<T>& lhs, const optional<U>& rhs) {
+      if (!lhs.has_value())
+          return true;
+      if (!rhs.has_value())
+          return false;
+
+      return lhs.value() <= rhs.value();
+  }
+  }
+  template <class T, class U>
+  inline constexpr bool operator>=(const optional<T>& lhs, const optional<U>& rhs) {
+      if (!rhs.has_value())
+          return true;
+      if (!lhs.has_value())
+          return false;
+
+      return lhs.value() >= rhs.value();
+  }
+
+  // [optional.nullops], comparison with nullopt
+template <class T> inline constexpr bool operator==(const optional<T>& lhs, nullopt_t) noexcept {
+    return !lhs.has_value();
+}
+template <class T> inline constexpr bool operator==(nullopt_t, const optional<T>& rhs) noexcept {
+    return !rhs.has_value();
+}
+template <class T> inline constexpr bool operator!=(const optional<T>& lhs, nullopt_t) noexcept {
+    return lhs.has_value();
+}
+template <class T> inline constexpr bool operator!=(nullopt_t, const optional<T>& rhs) noexcept {
+    return rhs.has_value();
+}
+template <class T> inline constexpr bool operator<(const optional<T>&, nullopt_t) noexcept {
+    return false;
+}
+template <class T> inline constexpr bool operator<(nullopt_t, const optional<T>& rhs) noexcept {
+    return rhs.has_value();
+}
+template <class T> inline constexpr bool operator<=(const optional<T>& lhs, nullopt_t) noexcept {
+    return !lhs.has_value();
+}
+template <class T> inline constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept {
+    return true;
+}
+template <class T> inline constexpr bool operator>(const optional<T>& lhs, nullopt_t) noexcept {
+    return lhs.has_value();
+}
+template <class T> inline constexpr bool operator>(nullopt_t, const optional<T>&) noexcept {
+    return false;
+}
+template <class T> inline constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept {
+    return true;
+}
+template <class T> inline constexpr bool operator>=(nullopt_t, const optional<T>& rhs) noexcept {
+    return !rhs.has_value();
+}
+
+  // [optional.comp_with_t], comparison with T
+template <class T, class U> inline constexpr bool operator==(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? *lhs == rhs : false;
+}
+template <class T, class U> inline constexpr bool operator==(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs == rhs.value() : false;
+}
+template <class T, class U> inline constexpr bool operator!=(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? lhs.value() != lhs : true;
+}
+template <class T, class U> inline constexpr bool operator!=(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs != rhs.value() : true;
+}
+template <class T, class U> inline constexpr bool operator<(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? lhs.value() < lhs : true;
+}
+template <class T, class U> inline constexpr bool operator<(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs < rhs.value() : false;
+}
+template <class T, class U> inline constexpr bool operator<=(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? lhs.value() <= lhs : true;
+}
+template <class T, class U> inline constexpr bool operator<=(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs <= rhs.value() : false;
+}
+template <class T, class U> inline constexpr bool operator>(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? lhs.value() > lhs : false;
+}
+template <class T, class U> inline constexpr bool operator>(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs > rhs.value() : true;
+}
+template <class T, class U> inline constexpr bool operator>=(const optional<T>& lhs, const U& rhs) {
+    return lhs.has_value() ? lhs.value() >= lhs : false;
+}
+template <class T, class U> inline constexpr bool operator>=(const U& lhs, const optional<T>& rhs) {
+    return rhs.has_value() ? lhs >= rhs.value() : true;
+}
+
+
+  // [optional.specalg], specialized algorithms
+template <class T, tl::enable_if_t<std::is_move_constructible<T>::value* = nullptr,
+                   tl:enable_if_t<std::is_swappable_v<T>>* = nullptr>
+void swap(optional<T>& lhs, optional<T>& rhs) noexcept(noexcept(lhs.swap(rhs))) {
+    return lhs.swap(rhs);
+}
+
+  template <class T>
+  inline constexpr optional<tl::decay_t<T>> make_optional(T&& v) {
+      return optional<decay_t<T>>(std​::​forward<T>(v));
+  }
+  template <class T, class... Args>
+  inline constexpr optional<T> make_optional(Args&&... args) {
+      return optional<T>(in_place, std​::​forward<Args>(args)...);
+  }
+  template <class T, class U, class... Args>
+  inline constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args) {
+      return optional<T>(in_place, il, std​::​forward<Args>(args)...);
+  }
+}
+
+  // [optional.hash], hash support
+namespace std {
+    template <class T> struct hash;
+    template <class T, class = decltype(hash<tl::remove_const_t<T>>{})>
+    struct hash<tl::optional<T>> {
+        std::size_t operator() (const tl::optional<T>& o) {
+            if (!o.has_value())
+                return 0;
+
+            return hash<tl::remove_const_t<T>>()(o.value());
+        }
+    }
+}
+
+namespace tl {
+
+template <class T>
+  class optional {
+  public:
+    using value_type = T;
+
+    // [optional.ctor], constructors
+    constexpr optional() noexcept : m_has_value(false) {
+        new (&m_storage.d) dummy;
+    }
+    constexpr optional(nullopt_t) noexcept : optional() {}
+
+    constexpr optional(const optional& rhs);
+    constexpr optional(optional&&) noexcept(see below);
+    template <class... Args>
+      constexpr explicit optional(in_place_t, Args&&...);
+    template <class U, class... Args>
+      constexpr explicit optional(in_place_t, initializer_list<U>, Args&&...);
+    template <class U = T>
+      EXPLICIT constexpr optional(U&&);
+    template <class U>
+      EXPLICIT optional(const optional<U>&);
+    template <class U>
+      EXPLICIT optional(optional<U>&&);
+
+    // [optional.dtor], destructor
+    ~optional();
+
+    // [optional.assign], assignment
+    optional& operator=(nullopt_t) noexcept;
+    optional& operator=(const optional&);
+    optional& operator=(optional&&) noexcept(see below);
+    template <class U = T> optional& operator=(U&&);
+    template <class U> optional& operator=(const optional<U>&);
+    template <class U> optional& operator=(optional<U>&&);
+    template <class... Args> T& emplace(Args&&...);
+    template <class U, class... Args> T& emplace(initializer_list<U>, Args&&...);
+
+    // [optional.swap], swap
+    void swap(optional&) noexcept(see below);
+
+    // [optional.observe], observers
+    constexpr const T* operator->() const {
+        return std::addressof(m_storage.t);
+    }
+    constexpr T* operator->() {
+        return std::addressof(m_storage.t);
+    }
+    constexpr const T& operator*() const& {
+        return m_storage.t;
+    }
+    constexpr T& operator*() & {
+        return m_storage.t;
+    }
+    constexpr T&& operator*() && {
+        return std::move(m_storage.t);
+    }
+    constexpr const T&& operator*() const&& {
+        return std::move(m_storage.t);
+    }
+    constexpr explicit operator bool() const noexcept {
+        return m_has_value;
+    }
+    constexpr bool has_value() const noexcept {
+        return m_has_value;
+    }
+    constexpr const T& value() const& {
+        return has_value() ? m_storage.t : throw bad_optional_access();
+    }
+    constexpr T& value() & {
+        return has_value() ? m_storage.t : throw bad_optional_access();
+    }
+    constexpr T&& value() && {
+        return has_value() ? std::move(m_storage.t) : throw bad_optional_access();
+    }
+    constexpr const T&& value() const&& {
+        return has_value() ? std::move(m_storage.t) : throw bad_optional_access();
+    }
+    template <class U> constexpr T value_or(U&&) const& {
+        static_assert(std::is_copy_constructible<T>::value && std::is_convertible<U&&, T>::value,
+                      "T must be copy constructible and convertible from U");
+        return has_value() ? value() : static_cast<T>(std::forward<U>(v));
+    }
+    template <class U> constexpr T value_or(U&&) && {
+        static_assert(std::is_move_constructible<T>::value && std::is_convertible<U&&, T>::value,
+                      "T must be move constructible and convertible from U");
+        return has_value() ? value() : static_cast<T>(std::forward<U>(v));
+    }
+
+    // [optional.mod], modifiers
+    void reset() noexcept;
+
+  private:
+    struct dummy{};
+    union {
+        dummy d;
+        T t;
+    } m_storage;
+
+    bool m_has_value;
+  };
+}