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diff --git a/include/ftl/optional.h b/include/ftl/optional.h
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+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <functional>
+#include <optional>
+#include <utility>
+
+#include <ftl/details/optional.h>
+
+namespace android::ftl {
+
+// Superset of std::optional<T> with monadic operations, as proposed in https://wg21.link/P0798R8.
+//
+// TODO: Remove in C++23.
+//
+template <typename T>
+struct Optional final : std::optional<T> {
+  using std::optional<T>::optional;
+
+  // Implicit downcast.
+  Optional(std::optional<T> other) : std::optional<T>(std::move(other)) {}
+
+  using std::optional<T>::has_value;
+  using std::optional<T>::value;
+
+  // Returns Optional<U> where F is a function that maps T to U.
+  template <typename F>
+  constexpr auto transform(F&& f) const& {
+    using R = details::transform_result_t<F, decltype(value())>;
+    if (has_value()) return R(std::invoke(std::forward<F>(f), value()));
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto transform(F&& f) & {
+    using R = details::transform_result_t<F, decltype(value())>;
+    if (has_value()) return R(std::invoke(std::forward<F>(f), value()));
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto transform(F&& f) const&& {
+    using R = details::transform_result_t<F, decltype(std::move(value()))>;
+    if (has_value()) return R(std::invoke(std::forward<F>(f), std::move(value())));
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto transform(F&& f) && {
+    using R = details::transform_result_t<F, decltype(std::move(value()))>;
+    if (has_value()) return R(std::invoke(std::forward<F>(f), std::move(value())));
+    return R();
+  }
+
+  // Returns Optional<U> where F is a function that maps T to Optional<U>.
+  template <typename F>
+  constexpr auto and_then(F&& f) const& {
+    using R = details::and_then_result_t<F, decltype(value())>;
+    if (has_value()) return std::invoke(std::forward<F>(f), value());
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto and_then(F&& f) & {
+    using R = details::and_then_result_t<F, decltype(value())>;
+    if (has_value()) return std::invoke(std::forward<F>(f), value());
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto and_then(F&& f) const&& {
+    using R = details::and_then_result_t<F, decltype(std::move(value()))>;
+    if (has_value()) return std::invoke(std::forward<F>(f), std::move(value()));
+    return R();
+  }
+
+  template <typename F>
+  constexpr auto and_then(F&& f) && {
+    using R = details::and_then_result_t<F, decltype(std::move(value()))>;
+    if (has_value()) return std::invoke(std::forward<F>(f), std::move(value()));
+    return R();
+  }
+
+  // Returns this Optional<T> if not nullopt, or else the Optional<T> returned by the function F.
+  template <typename F>
+  constexpr auto or_else(F&& f) const& -> details::or_else_result_t<F, T> {
+    if (has_value()) return *this;
+    return std::forward<F>(f)();
+  }
+
+  template <typename F>
+  constexpr auto or_else(F&& f) && -> details::or_else_result_t<F, T> {
+    if (has_value()) return std::move(*this);
+    return std::forward<F>(f)();
+  }
+
+  // Delete new for this class. Its base doesn't have a virtual destructor, and
+  // if it got deleted via base class pointer, it would cause undefined
+  // behavior. There's not a good reason to allocate this object on the heap
+  // anyway.
+  static void* operator new(size_t) = delete;
+  static void* operator new[](size_t) = delete;
+};
+
+template <typename T, typename U>
+constexpr bool operator==(const Optional<T>& lhs, const Optional<U>& rhs) {
+  return static_cast<std::optional<T>>(lhs) == static_cast<std::optional<U>>(rhs);
+}
+
+template <typename T, typename U>
+constexpr bool operator!=(const Optional<T>& lhs, const Optional<U>& rhs) {
+  return !(lhs == rhs);
+}
+
+// Deduction guides.
+template <typename T>
+Optional(T) -> Optional<T>;
+
+template <typename T>
+Optional(std::optional<T>) -> Optional<T>;
+
+}  // namespace android::ftl