From ec2c81fc569f8935c6ef1c466cb0781b427404cf Mon Sep 17 00:00:00 2001
From: CHatingPython <chatingpython@kpgpmc.org>
Date: Thu, 18 Jun 2026 23:58:37 +0200
Subject: [PATCH] refactor(furvm): improve the handle system

Absolute slop

Refs: #12
---
 furlang/include/furlang/arena.hpp     |  51 ++++-
 furvm/include/furvm/context.hpp       | 152 +++++--------
 furvm/include/furvm/detail/handle.hpp |  24 ++
 furvm/include/furvm/executor.hpp      |  15 +-
 furvm/include/furvm/fwd.hpp           |  46 ++--
 furvm/include/furvm/handle.hpp        | 315 ++++++++++++++++++--------
 furvm/include/furvm/module.hpp        |  83 +++----
 furvm/include/furvm/thing.hpp         | 213 +++++++++++++----
 furvm/src/context.cpp                 |  10 +-
 furvm/src/executor.cpp                |  69 +++---
 furvm/src/main.cpp                    |   3 +-
 furvm/src/serializer.cpp              |  49 ++--
 furvm/src/thing.cpp                   | 228 -------------------
 13 files changed, 641 insertions(+), 617 deletions(-)
 create mode 100644 furvm/include/furvm/detail/handle.hpp
 delete mode 100644 furvm/src/thing.cpp

diff --git a/furlang/include/furlang/arena.hpp b/furlang/include/furlang/arena.hpp
index ef87d97..58dce98 100644
--- a/furlang/include/furlang/arena.hpp
+++ b/furlang/include/furlang/arena.hpp
@@ -106,6 +106,55 @@ private:
     region*     m_tail = nullptr;
 };
 
+template <typename T>
+class arena_allocator {
+    template <typename>
+    friend class arena_allocator;
+public:
+    using value_type = T;
+public:
+    explicit arena_allocator(arena& arena) noexcept
+      : m_arena(&arena) {}
+
+    template <typename U>
+    arena_allocator(const arena_allocator<U>& other) noexcept
+      : m_arena(other.m_arena) {}
+
+    template <typename U>
+    arena_allocator& operator=(const arena_allocator<U>& other) noexcept {
+        if (this == &other) return *this;
+        m_arena = other.m_arena;
+        return *this;
+    }
+
+    template <typename U>
+    arena_allocator(arena_allocator<U>&& other) noexcept
+      : m_arena(std::move(other.m_arena)) {}
+
+    template <typename U>
+    arena_allocator& operator=(arena_allocator<U>&& other) noexcept {
+        if (this == &other) return *this;
+        m_arena = std::move(other.m_arena);
+        return *this;
+    }
+public:
+    [[nodiscard]] T* allocate(std::size_t count = 1) { return m_arena->allocate<T>(count); }
+
+    void deallocate(T* ptr, std::size_t count) noexcept {}
+public:
+    template <typename U>
+    bool operator==(const arena_allocator<U>& other) const noexcept {
+        return m_arena == other.m_arena;
+    }
+
+    template <typename U>
+    bool operator!=(const arena_allocator<U>& other) const noexcept {
+        return m_arena != other.m_arena;
+    }
+private:
+    arena* m_arena;
+};
+
 } // namespace furlang
 
-#endif // FURLANG_ARENA_HPP
\ No newline at end of file
+#endif // FURLANG_ARENA_HPP
diff --git a/furvm/include/furvm/context.hpp b/furvm/include/furvm/context.hpp
index f2e9298..e1203dd 100644
--- a/furvm/include/furvm/context.hpp
+++ b/furvm/include/furvm/context.hpp
@@ -4,24 +4,18 @@
 #include "furlang/arena.hpp"
 #include "furvm/executor.hpp"
 #include "furvm/fwd.hpp"
-#include "furvm/module.hpp"
-#include "furvm/thing.hpp"
+#include "furvm/handle.hpp"
+#include "furvm/module.hpp" // IWYU pragma: keep
+#include "furvm/thing.hpp"  // IWYU pragma: keep
 
-#include <cstring>
-#include <memory>
-#include <queue>
-#include <string>
-#include <type_traits>
-#include <unordered_map>
+#include <cstddef>
 #include <utility>
-#include <vector>
 
 namespace furvm {
 
 class context {
 public:
     friend class executor;
-    friend class thing;
 public:
     context();
     ~context() = default;
@@ -39,105 +33,77 @@ public:
     context(const context&)            = delete;
     context& operator=(const context&) = delete;
 public:
-    /**
-     * @brief Emplaces a new module in this context.
-     *
-     * @param args Arguments to forward to module's constructor.
-     * @return A handle to the module.
-     */
-    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<mod, Args...>>>
-    mod_h emplace_module(Args&&... args) {
-        mod_p       mod  = std::make_shared<class mod>(std::forward<Args>(args)...);
-        std::string name = mod->name();
-        return { name, m_modules[name] = std::move(mod) };
+    template <typename... Args>
+    auto emplace_module(Args&&... args) {
+        return m_modules.emplace(std::forward<Args>(args)...);
     }
 
-    /**
-     * @brief Erases a module from this context.
-     *
-     * @param name Name of the module to erase.
-     * @return A shared pointer to the erased module.
-     */
-    template <typename Name>
-    mod_p erase_module(Name&& name) {
-        return std::move(m_modules.erase(std::forward<Name>(name))->second);
+    template <typename... Args>
+    auto module_at(Args&&... args) {
+        return m_modules.at(std::forward<Args>(args)...);
     }
 
-    /**
-     * @brief Returns a module of this context.
-     *
-     * @param name Name of the module.
-     * @return The module.
-     */
-    template <typename Name>
-    constexpr mod_p& module_at(Name&& name) {
-        return m_modules.at(std::forward<Name>(name));
+    template <typename... Args>
+    auto module_at(Args&&... args) const {
+        return m_modules.at(std::forward<Args>(args)...);
     }
 
-    /**
-     * @brief Returns a module of this context.
-     *
-     * @param name Name of the module.
-     * @return The module.
-     */
-    template <typename Name>
-    constexpr const mod_p& module_at(Name&& name) const {
-        return m_modules.at(std::forward<Name>(name));
+    template <typename... Args>
+    auto erase_module(Args&&... args) {
+        return m_modules.erase(std::forward<Args>(args)...);
     }
-
-    /**
-     * @brief Returns how many does this context have modules.
-     *
-     * @return The module count.
-     */
-    constexpr size_t module_count() const { return m_modules.size(); }
 public:
-    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<executor, Args...>>>
-    executor_h emplace_executor(Args&&... args) {
-        executor    executor(std::forward<Args>(args)...);
-        executor_id id = m_executors.size();
-        m_executors.emplace_back(std::move(executor));
-        return { id, m_executors[id] };
+    template <typename... Args>
+    auto emplace_executor(Args&&... args) {
+        return m_executors.emplace_back(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto executor_at(Args&&... args) {
+        return m_executors.at(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto executor_at(Args&&... args) const {
+        return m_executors.at(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto erase_executor(Args&&... args) {
+        return m_executors.erase(std::forward<Args>(args)...);
+    }
+public:
+    template <typename... Args>
+    auto emplace_thing(Args&&... args) {
+        return m_things.emplace_back(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto thing_at(Args&&... args) {
+        return m_things.at(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto thing_at(Args&&... args) const {
+        return m_things.at(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    auto erase_thing(Args&&... args) {
+        return m_things.erase(std::forward<Args>(args)...);
     }
 public:
     /**
      * @brief Removes unreferenced things from the thing list.
      */
     void collect();
-public:
-    thing_h emplace_thing(thing_t type) {
-        thing_id id = m_things.size();
-        if (!m_deadThings.empty()) {
-            id = m_deadThings.front();
-            m_deadThings.pop();
-        }
-
-        size_t size = thing_type_size(type);
-        void*  data = nullptr;
-        for (auto it = m_deadThingData.begin(); it != m_deadThingData.end(); ++it) {
-            thing_t curType{};
-            std::memcpy(&curType, static_cast<char*>(*it) - sizeof(curType), sizeof(curType));
-            if (thing_type_size(curType) != size) continue;
-            data = *it;
-            m_deadThingData.erase(it);
-            break;
-        }
-        if (data == nullptr) data = m_thingArena.allocate<char>(sizeof(thing_t) + size);
-        memcpy(data, &type, sizeof(type));
-        data = static_cast<char*>(data) + sizeof(type);
-
-        thing_p thing = std::make_shared<class thing>(type, data);
-        return { id, m_things.emplace_back(std::move(thing)) };
-    }
 private:
-    std::unordered_map<std::string, mod_p> m_modules;
+    handle_container<mod_h>      m_modules;
+    handle_container<thing_h>    m_things;
+    handle_container<executor_h> m_executors;
 
-    std::vector<thing_p>  m_things;
-    std::vector<executor> m_executors;
-
-    std::queue<thing_id> m_deadThings;
-    std::vector<void*>   m_deadThingData;
-    furlang::arena       m_thingArena;
+    furlang::arena             m_thingArena;
+    thing_allocator<std::byte> m_thingAllocator;
 };
 
 } // namespace furvm
diff --git a/furvm/include/furvm/detail/handle.hpp b/furvm/include/furvm/detail/handle.hpp
new file mode 100644
index 0000000..e426c33
--- /dev/null
+++ b/furvm/include/furvm/detail/handle.hpp
@@ -0,0 +1,24 @@
+#ifndef FURVM_DETAIL_HANDLE_HPP
+#define FURVM_DETAIL_HANDLE_HPP
+
+#include <type_traits>
+
+namespace furvm {
+namespace detail {
+
+template <typename Header, typename = void>
+struct header_has_refcount : std::false_type {};
+
+template <typename Header>
+struct header_has_refcount<Header,
+    std::void_t<decltype(std::declval<Header&>().acquire()),
+        decltype(std::declval<Header&>().release()),
+        decltype(std::declval<Header&>().reference_count())>> : std::true_type {};
+
+template <typename Header>
+static constexpr auto header_has_refcount_v = header_has_refcount<Header>::value;
+
+} // namespace detail
+} // namespace furvm
+
+#endif // FURVM_DETAIL_HANDLE_HPP
diff --git a/furvm/include/furvm/executor.hpp b/furvm/include/furvm/executor.hpp
index b550789..ae60589 100644
--- a/furvm/include/furvm/executor.hpp
+++ b/furvm/include/furvm/executor.hpp
@@ -2,8 +2,11 @@
 #define FURVM_EXECUTOR_HPP
 
 #include "furvm/fwd.hpp"
+#include "furvm/module.hpp" // IWYU pragma: keep
+#include "furvm/thing.hpp"  // IWYU pragma: keep
 
 #include <stack>
+#include <utility>
 #include <vector>
 
 namespace furvm {
@@ -99,19 +102,17 @@ public:
      */
     frame frame() const;
 public:
-    /**
-     * @brief Pushes a thing onto the stack.
-     *
-     * @param thing The thing to push.
-     */
-    void push_thing(const thing_h& thing);
+    template <typename HandleFwd>
+    void push_thing(HandleFwd&& handle) {
+        m_stack.emplace(std::forward<HandleFwd>(handle));
+    }
 
     /**
      * @brief Pushes a thing onto the stack.
      *
      * @param thing The thing to push.
      */
-    void push_thing(thing_h&& thing);
+    thing_h push_thing(class thing<>&& thing);
 
     /**
      * @brief Pops a thing from the stack.
diff --git a/furvm/include/furvm/fwd.hpp b/furvm/include/furvm/fwd.hpp
index d947449..6c4c822 100644
--- a/furvm/include/furvm/fwd.hpp
+++ b/furvm/include/furvm/fwd.hpp
@@ -1,8 +1,6 @@
 #ifndef FURVM_FWD_HPP
 #define FURVM_FWD_HPP
 
-#include "furvm/handle.hpp"
-
 #include <cstddef> // IWYU pragma: export
 #include <cstdint> // IWYU pragma: export
 #include <memory>
@@ -25,6 +23,24 @@ using byte = std::uint8_t;
  */
 using bytecode_pos = std::uint64_t;
 
+/**
+ * @brief Handle header with reference count.
+ */
+template <typename Id>
+class refcount_header;
+
+/**
+ * @brief Generic handle header.
+ */
+template <typename Id>
+class generic_header;
+
+/**
+ * @brief Handle.
+ */
+template <typename Value, typename Header>
+class handle;
+
 // constant.hpp
 
 /**
@@ -76,11 +92,6 @@ enum class function_t : std::uint8_t;
  */
 class function;
 
-/**
- * @brief An alias to a function shared pointer.
- */
-using function_p = std::shared_ptr<function>;
-
 /**
  * @brief Furvm function's index.
  */
@@ -89,7 +100,7 @@ using function_id = std::uint16_t;
 /**
  * @brief A handle to a furvm function.
  */
-using function_h = handle<function_id, function>;
+using function_h = handle<function, refcount_header<function_id>>;
 
 // module.hpp
 
@@ -114,7 +125,7 @@ using mod_id = std::string;
 /**
  * @brief A handle to a furvm module.
  */
-using mod_h = handle<mod_id, mod_p>;
+using mod_h = handle<mod, refcount_header<mod_id>>;
 
 // thing.hpp
 
@@ -130,28 +141,27 @@ enum class thing_t : std::uint8_t;
  */
 class bad_thing_access;
 
+template <typename T>
+class thing_allocator;
+
 /**
  * @class thing
  * @brief Furvm thing.
  *
  * A stack element. Think of it like of a value in C++ or I guess a class in java.
  */
+template <template <typename> typename Allocator = thing_allocator>
 class thing;
 
-/**
- * @brief An alias to a thing shared pointer.
- */
-using thing_p = std::shared_ptr<thing>;
-
 /**
  * @brief Furvm thing's index.
  */
 using thing_id = std::uint32_t;
 
 /**
- * @brief A handle to a furvm's thing.
+ * @brief A handle to a thing.
  */
-using thing_h = handle<thing_id, thing_p>;
+using thing_h = handle<thing<thing_allocator>, refcount_header<thing_id>>;
 
 // executor.hpp
 
@@ -185,9 +195,9 @@ using executor_p = std::shared_ptr<executor>;
 using executor_id = std::uint32_t;
 
 /**
- * @brief A handle to a furvm's executor.
+ * @brief A handle to an executor.
  */
-using executor_h = handle<executor_id, executor>;
+using executor_h = handle<executor, refcount_header<executor_id>>;
 
 // context.hpp
 
diff --git a/furvm/include/furvm/handle.hpp b/furvm/include/furvm/handle.hpp
index 7f10bfc..bf7c84a 100644
--- a/furvm/include/furvm/handle.hpp
+++ b/furvm/include/furvm/handle.hpp
@@ -1,118 +1,237 @@
 #ifndef FURVM_HANDLE_HPP
 #define FURVM_HANDLE_HPP
 
-#include <limits>
+#include "furvm/detail/handle.hpp"
+#include "furvm/fwd.hpp"
+
+#include <atomic>
+#include <tuple>
 #include <type_traits>
+#include <unordered_map>
 #include <utility>
+#include <vector>
 
 namespace furvm {
 
-namespace detail {
+template <typename Handle, typename = void>
+class handle_container;
 
-template <typename Id, typename = void>
-struct dead_id {
-    static constexpr Id value = {};
+// TODO: Implement generational indexes
+
+template <typename Id>
+class refcount_header {
+public:
+    using id_type       = Id;
+    using refcount_type = std::uint32_t;
+public:
+    template <typename IdFwd>
+    refcount_header(IdFwd&& id, refcount_type refCount)
+      : m_id(std::forward<IdFwd>(id)), m_refCount(refCount) {}
+public:
+    refcount_type reference_count() const { return m_refCount; }
+
+    void acquire() { ++m_refCount; }
+
+    void release() { --m_refCount; }
+public:
+    id_type id() const { return m_id; }
+private:
+    id_type                    m_id;
+    std::atomic<refcount_type> m_refCount;
 };
 
 template <typename Id>
-struct dead_id<Id, std::enable_if_t<std::is_integral_v<Id>>> {
-    static constexpr Id value = std::numeric_limits<Id>::max();
-};
-
-} // namespace detail
-
-template <typename Id, typename T>
-class handle {
+class generic_header {
 public:
     using id_type = Id;
-
-    using value_type      = T;
-    using reference       = T&;
-    using const_reference = const T&;
-    using pointer         = T*;
-    using const_pointer   = const T*;
 public:
-    /**
-     * @brief Returns a new handle.
-     *
-     * @param id Id of the handle.
-     * @param value Value of the handle.
-     */
-    template <typename IdF, typename Value>
-    handle(IdF&& id, Value&& value)
-      : m_id(std::forward<IdF>(id)), m_value(std::forward<Value>(value)) {}
-
-    handle()
-      : m_id(detail::dead_id<Id>::value), m_value() {}
+    generic_header(id_type id)
+      : m_id(id) {}
 public:
-    handle& operator=(value_type&& value) noexcept {
-        m_value = std::move(value);
-        return *this;
-    }
-
-    handle& operator=(const value_type& value) noexcept {
-        m_value = value;
-        return *this;
-    }
-public:
-    /**
-     * @brief Returns the handle's id.
-     *
-     * @return The id.
-     */
-    constexpr Id id() const { return m_id; }
-
-    /**
-     * @brief Returns the handle's pointer.
-     *
-     * @return The pointer.
-     */
-    reference value() { return m_value; }
-
-    /**
-     * @brief Returns the handle's pointer.
-     *
-     * @return The pointer.
-     */
-    const_reference value() const { return m_value; }
-public:
-    /**
-     * @brief Returns the handle's id.
-     *
-     * @return The id.
-     */
-    explicit operator Id() const { return m_id; }
-public:
-    /**
-     * @brief Returns a reference to the handle's value.
-     *
-     * @return The value.
-     */
-    reference operator*() { return m_value; }
-
-    /**
-     * @brief Returns a reference to the handle's value.
-     *
-     * @return The value.
-     */
-    const_reference operator*() const { return m_value; }
-
-    /**
-     * @brief Returns a pointer to the handle's value.
-     *
-     * @return The value pointer.
-     */
-    pointer operator->() { return &m_value; }
-
-    /**
-     * @brief Returns a pointer to the handle's value.
-     *
-     * @return The value pointer.
-     */
-    const_pointer operator->() const { return &m_value; }
+    id_type id() const { return m_id; }
 private:
-    id_type    m_id;
-    value_type m_value;
+    id_type m_id;
+};
+
+template <typename Value, typename Header = refcount_header<std::uint32_t>>
+class handle {
+public:
+    using value_type      = Value;
+    using reference       = Value&;
+    using const_reference = const Value&;
+    using pointer         = Value*;
+    using const_pointer   = const Value*;
+public:
+    using id_type = typename Header::id_type;
+public:
+    using pair_type = std::pair<Header, Value>;
+public:
+    handle() = default;
+
+    handle(pair_type* value)
+      : m_value(value) {
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            m_value->first.acquire();
+        }
+    }
+
+    ~handle() {
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            if (m_value != nullptr) m_value->first.release();
+        }
+        m_value = nullptr;
+    }
+
+    handle(handle&& other) noexcept
+      : m_value(other.m_value) {
+        other.m_value = nullptr;
+    }
+
+    handle& operator=(handle&& other) noexcept {
+        if (this == &other) return *this;
+        m_value       = other.m_value;
+        other.m_value = nullptr;
+        return *this;
+    }
+
+    handle(const handle& other)
+      : m_value(other.m_value) {
+        m_value->first.acquire();
+    }
+
+    handle& operator=(const handle& other) {
+        if (this == &other) return *this;
+        m_value = other.m_value;
+        m_value->first.acquire();
+        return *this;
+    }
+public:
+    id_type id() const { return m_value->first.id(); }
+
+    bool empty() const { return m_value == nullptr; }
+
+    template <typename ReferenceCount = typename Header::refcount_type>
+    ReferenceCount reference_count() const {
+        return m_value->first.reference_count();
+    }
+
+    pointer       operator->() { return &m_value->second; }
+    const_pointer operator->() const { return &m_value->second; }
+
+    reference       operator*() { return m_value->second; }
+    const_reference operator*() const { return m_value->second; }
+
+    reference       value() { return m_value->second; }
+    const_reference value() const { return m_value->second; }
+private:
+    pair_type* m_value = nullptr;
+};
+
+template <typename Handle>
+class handle_container<Handle, std::enable_if_t<!std::is_integral_v<typename Handle::id_type>>> {
+private:
+    using pair_type = typename Handle::pair_type;
+public:
+    using value_type  = std::remove_cv_t<std::remove_reference_t<Handle>>;
+    using const_value = std::add_const_t<value_type>;
+
+    using id_type = typename Handle::id_type;
+public:
+    handle_container()  = default;
+    ~handle_container() = default;
+
+    handle_container(handle_container&&) noexcept            = default;
+    handle_container& operator=(handle_container&&) noexcept = default;
+
+    handle_container(const handle_container&)            = delete;
+    handle_container& operator=(const handle_container&) = delete;
+public:
+    template <typename IdFwd,
+        typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename pair_type::second_type, Args...>>>
+    value_type emplace(IdFwd&& id, Args&&... args) {
+        id_type idFwd = std::forward<IdFwd>(id);
+        if (auto it = m_pairs.find(idFwd); it != m_pairs.end()) delete it->second;
+        auto pair = new pair_type(std::piecewise_construct,
+            std::forward_as_tuple(idFwd, 0),
+            std::forward_as_tuple(std::forward<Args>(args)...));
+        m_pairs.emplace(std::move(idFwd), pair);
+        return { pair };
+    }
+
+    template <typename IdFwd>
+    value_type at(IdFwd&& id) {
+        return { m_pairs.at(std::forward<IdFwd>(id)) };
+    }
+
+    template <typename IdFwd>
+    const_value at(IdFwd&& id) const {
+        return { m_pairs.at(std::forward<IdFwd>(id)) };
+    }
+
+    template <typename IdFwd>
+    void erase(IdFwd&& id) {
+        auto it = m_pairs.find(std::forward<IdFwd>(id));
+        if (it == m_pairs.end()) return;
+        delete it->second;
+        m_pairs.erase(it);
+    }
+private:
+    std::unordered_map<id_type, pair_type*> m_pairs;
+};
+
+template <typename Handle>
+class handle_container<Handle, std::enable_if_t<std::is_integral_v<typename Handle::id_type>>> {
+private:
+    using pair_type = typename Handle::pair_type;
+public:
+    using value_type  = std::remove_cv_t<std::remove_reference_t<Handle>>;
+    using const_value = std::add_const_t<value_type>;
+
+    using id_type = typename Handle::id_type;
+public:
+    handle_container()  = default;
+    ~handle_container() = default;
+
+    handle_container(handle_container&&) noexcept            = default;
+    handle_container& operator=(handle_container&&) noexcept = default;
+
+    handle_container(const handle_container&)            = delete;
+    handle_container& operator=(const handle_container&) = delete;
+public:
+    template <typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename pair_type::second_type, Args...>>>
+    value_type emplace(id_type id, Args&&... args) {
+        if (id >= m_pairs.size()) {
+            m_pairs.resize(id + 1, nullptr);
+        } else if (m_pairs[id] != nullptr) {
+            delete m_pairs[id];
+        }
+
+        pair_type* newPair = new pair_type(std::piecewise_construct,
+            std::forward_as_tuple(id, 0),
+            std::forward_as_tuple(std::forward<Args>(args)...));
+
+        m_pairs[id] = newPair;
+        return { newPair };
+    }
+
+    template <typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename Handle::pair_type::second_type, Args...>>>
+    value_type emplace_back(Args&&... args) {
+        return emplace(static_cast<id_type>(m_pairs.size()), std::forward<Args>(args)...);
+    }
+
+    value_type  at(id_type id) { return { m_pairs.at(id) }; }
+    const_value at(id_type id) const { return { m_pairs.at(id) }; }
+
+    void erase(id_type id) {
+        if (id >= m_pairs.size()) return;
+        delete m_pairs[id];
+        m_pairs[id] = nullptr;
+    }
+private:
+    std::vector<pair_type*> m_pairs;
 };
 
 } // namespace furvm
diff --git a/furvm/include/furvm/module.hpp b/furvm/include/furvm/module.hpp
index c0d8e9b..02ba7b0 100644
--- a/furvm/include/furvm/module.hpp
+++ b/furvm/include/furvm/module.hpp
@@ -3,8 +3,8 @@
 
 #include "furvm/function.hpp"
 #include "furvm/fwd.hpp"
+#include "furvm/handle.hpp"
 
-#include <stdexcept>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -24,21 +24,9 @@ public:
      * @param name Name of this module.
      * @param args Arguments to forward to bytecode's constructor.
      */
-    template <typename Name,
-        typename... Args,
-        typename = std::enable_if_t<std::is_constructible_v<bytecode_t, Args...>>>
-    mod(Name&& name, Args&&... args)
-      : m_name(std::forward<Name>(name)), m_bytecode(std::forward<Args>(args)...) {}
-
-    /**
-     * @brief Construct a new module.
-     *
-     * @param name C-string name of this module.
-     * @param args Arguments to forward to bytecode's constructor.
-     */
     template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<bytecode_t, Args...>>>
-    mod(const char* name, Args&&... args)
-      : m_name(name), m_bytecode(std::forward<Args>(args)...) {}
+    mod(Args&&... args)
+      : m_bytecode(std::forward<Args>(args)...) {}
 
     ~mod() = default;
 
@@ -55,13 +43,6 @@ public:
     mod(const mod&)            = delete;
     mod& operator=(const mod&) = delete;
 public:
-    /**
-     * @brief Returns this module's name.
-     *
-     * @return The name.
-     */
-    constexpr const std::string& name() const { return m_name; }
-
     /**
      * @brief Returns a byte from bytecode of this module.
      *
@@ -84,41 +65,37 @@ public:
      */
     constexpr const bytecode_t& bytecode() const { return m_bytecode; }
 public:
-    /**
-     * @brief Returns a function from this module.
-     *
-     * @param name Name of the function.
-     * @return The function.
-     */
-    template <typename Name>
-    function_h function_at(Name&& name) const {
-        if (auto it = m_functionMap.find(std::forward<Name>(name)); it != m_functionMap.end()) return it->second;
-        throw std::runtime_error("invalid function");
-    }
-
-    /**
-     * @brief Returns a function from this module.
-     *
-     * @param id Id of the function.
-     * @return The function.
-     */
-    function_h function_at(function_id id) const { return { id, m_functions.at(id) }; }
-
     template <typename... Args>
     function_h emplace_function(Args&&... args) {
-        function    function(std::forward<Args>(args)...);
-        std::string name   = function.name();
-        function_id id     = m_functions.size();
-        function_h  handle = { id, m_functions.emplace_back(std::move(function)) };
-        m_functionMap.emplace(std::move(name), handle);
-        return handle;
+        function_h function             = m_functions.emplace_back(std::forward<Args>(args)...);
+        m_functionMap[function->name()] = function.id();
+        return std::move(function);
     }
-private:
-    std::string m_name;
-    bytecode_t  m_bytecode;
 
-    std::unordered_map<std::string, function_h> m_functionMap;
-    std::vector<function>                       m_functions;
+    template <typename FunctionHandle>
+    void push_back(FunctionHandle&& handle) {
+        m_functions.emplace_back(std::forward<FunctionHandle>(handle));
+    }
+
+    auto function_at(function_id id) { return m_functions.at(id); }
+    auto function_at(function_id id) const { return m_functions.at(id); }
+
+    template <typename NameFwd>
+    auto function_at(NameFwd&& name) {
+        return function_at(m_functionMap.at(std::forward<NameFwd>(name)));
+    }
+
+    template <typename NameFwd>
+    auto function_at(NameFwd&& name) const {
+        return function_at(m_functionMap.at(std::forward<NameFwd>(name)));
+    }
+
+    void erase_function(function_id id) { m_functions.erase(id); }
+private:
+    bytecode_t m_bytecode;
+
+    std::unordered_map<std::string, function_id> m_functionMap;
+    handle_container<function_h>                 m_functions;
 };
 
 } // namespace furvm
diff --git a/furvm/include/furvm/thing.hpp b/furvm/include/furvm/thing.hpp
index 1320a0c..f0a916e 100644
--- a/furvm/include/furvm/thing.hpp
+++ b/furvm/include/furvm/thing.hpp
@@ -1,8 +1,15 @@
 #ifndef FURVM_THING_HPP
 #define FURVM_THING_HPP
 
+#include "furlang/arena.hpp"
 #include "furvm/fwd.hpp"
 
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <utility>
+#include <vector>
+
 namespace furvm {
 
 enum class thing_t : std::uint8_t {
@@ -15,7 +22,12 @@ enum class thing_t : std::uint8_t {
  * @param type Type of the thing.
  * @return The data size of the thing.
  */
-std::size_t thing_type_size(thing_t type);
+static inline std::size_t thing_type_size(thing_t type) {
+    switch (type) {
+    case thing_t::Int32: return sizeof(std::int32_t);
+    default: return 0;
+    }
+}
 
 class bad_thing_access : public std::exception {
 public:
@@ -50,28 +62,40 @@ public:
     const char* what() const noexcept override { return "bad thing access"; }
 };
 
+template <template <typename> typename Allocator>
 class thing final {
     friend class executor;
 public:
-    using nref_t = std::size_t; /**< Type of reference count. */
-
-    static constexpr thing_id GENERATION_SIZE = 12; /**< Bit size of generation part in thing_handle. */
+    using allocator_type = Allocator<std::byte>;
 public:
-    thing(thing_t type);
+    thing(thing_t type, const allocator_type& allocator = {})
+      : m_type(type), m_allocator(allocator) {
+        m_data = m_allocator.allocate(thing_type_size(type));
+    }
 
-    thing(thing_t type, void* data);
-
-    ~thing();
+    ~thing() { m_allocator.deallocate(m_data, thing_type_size(thing_t::Int32)); }
 
     /**
      * @brief Move constructor.
      */
-    thing(thing&&) noexcept;
+    thing(thing&& other) noexcept
+      : m_type(other.m_type), m_data(other.m_data), m_allocator(std::move(other.m_allocator)) {
+        other.m_type = {};
+        other.m_data = nullptr;
+    }
 
     /**
      * @brief Move constructor.
      */
-    thing& operator=(thing&&) noexcept;
+    thing& operator=(thing&& other) noexcept {
+        if (this == &other) return *this;
+        m_type       = other.m_type;
+        m_data       = other.m_data;
+        m_allocator  = std::move(other.m_allocator);
+        other.m_type = {};
+        other.m_data = nullptr;
+        return *this;
+    }
 
     thing(const thing&)            = delete;
     thing& operator=(const thing&) = delete;
@@ -82,55 +106,158 @@ public:
      * @param thing Thing to clone.
      * @return Shared pointer to a clone of the thing.
      */
-    static thing_h clone(const context_p& context, const thing_h& thing);
+    thing clone() const {
+        class thing res(m_type, m_allocator);
+        switch (m_type) {
+        default: {
+            std::memcpy(res.m_data, m_data, thing_type_size(m_type));
+        } break;
+        }
+        return std::move(res);
+    }
 public:
     /**
      * @brief Returns an int32 value from this thing.
      *
      * @return The value.
      */
-    std::int32_t& int32();
+    std::int32_t& int32() {
+        if (m_type != thing_t::Int32) throw bad_thing_access();
+        return *reinterpret_cast<std::int32_t*>(m_data);
+    }
 
     /**
      * @brief Returns an int32 value from this thing.
      *
      * @return The value.
      */
-    const std::int32_t& int32() const;
+    const std::int32_t& int32() const {
+        if (m_type != thing_t::Int32) throw bad_thing_access();
+        return *reinterpret_cast<std::int32_t*>(m_data);
+    }
 public:
-    thing_h add(const context_p& context, const thing_h& rhs) const;
-    thing_h sub(const context_p& context, const thing_h& rhs) const;
-    thing_h mul(const context_p& context, const thing_h& rhs) const;
-    thing_h div(const context_p& context, const thing_h& rhs) const;
-    thing_h mod(const context_p& context, const thing_h& rhs) const;
-    thing_h equals(const context_p& context, const thing_h& rhs) const;
-    thing_h not_equals(const context_p& context, const thing_h& rhs) const;
-    thing_h less_than(const context_p& context, const thing_h& rhs) const;
-    thing_h greater_than(const context_p& context, const thing_h& rhs) const;
-    thing_h less_equals(const context_p& context, const thing_h& rhs) const;
-    thing_h greater_equals(const context_p& context, const thing_h& rhs) const;
-public:
-    /**
-     * @brief Increments reference count of this thing by one.
-     */
-    void add_reference() { ++m_refCount; }
+    thing add(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() + rhs.int32();
+        return res;
+    }
 
-    /**
-     * @brief Decrements reference count of this thing by one.
-     */
-    void remove_reference() { --m_refCount; }
+    thing sub(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() - rhs.int32();
+        return res;
+    }
 
-    /**
-     * @brief Returns reference count of this thing.
-     *
-     * @return The reference count.
-     */
-    constexpr nref_t reference_count() const { return m_refCount; }
+    thing mul(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() * rhs.int32();
+        return res;
+    }
+
+    thing div(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() / rhs.int32();
+        return res;
+    }
+
+    thing mod(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() % rhs.int32();
+        return res;
+    }
+
+    thing equals(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() == rhs.int32();
+        return res;
+    }
+
+    thing not_equals(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() != rhs.int32();
+        return res;
+    }
+
+    thing less_than(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() < rhs.int32();
+        return res;
+    }
+
+    thing greater_than(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() > rhs.int32();
+        return res;
+    }
+
+    thing less_equals(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() <= rhs.int32();
+        return res;
+    }
+
+    thing greater_equals(const thing& rhs) const {
+        thing res(m_type, m_allocator);
+        res.int32() = int32() >= rhs.int32();
+        return res;
+    }
 private:
-    thing_t m_type;
-    bool    m_ownData  = true;
-    nref_t  m_refCount = 0;
-    void*   m_data     = nullptr;
+    thing_t    m_type{};
+    std::byte* m_data = nullptr;
+
+    allocator_type m_allocator;
+};
+
+template <typename T>
+class thing_allocator {
+    template <typename>
+    friend class thing_allocator;
+public:
+    using value_type = T;
+public:
+    explicit thing_allocator(furlang::arena& arena) noexcept
+      : m_arena(&arena) {}
+
+    template <typename U>
+    thing_allocator(const thing_allocator<U>& other) noexcept
+      : m_arena(other.m_arena), m_deadThings(other.m_deadThings) {}
+
+    template <typename U>
+    thing_allocator& operator=(const thing_allocator<U>& other) noexcept {
+        if (this == &other) return *this;
+        m_arena      = other.m_arena;
+        m_deadThings = other.m_deadThings;
+        return *this;
+    }
+
+    template <typename U>
+    thing_allocator(thing_allocator<U>&& other) noexcept
+      : m_arena(std::move(other.m_arena)) {}
+
+    template <typename U>
+    thing_allocator& operator=(thing_allocator<U>&& other) noexcept {
+        if (this == &other) return *this;
+        m_arena = std::move(other.m_arena);
+        return *this;
+    }
+public:
+    [[nodiscard]] T* allocate(std::size_t count = 1) { return m_arena->allocate<T>(count); }
+
+    void deallocate(T* ptr, std::size_t count) noexcept { m_deadThings.emplace_back(ptr, count); }
+public:
+    template <typename U>
+    bool operator==(const thing_allocator<U>& other) const noexcept {
+        return m_arena == other.m_arena && m_deadThings == other.m_deadThings;
+    }
+
+    template <typename U>
+    bool operator!=(const thing_allocator<U>& other) const noexcept {
+        return m_arena != other.m_arena || m_deadThings != other.m_deadThings;
+    }
+private:
+    furlang::arena* m_arena;
+
+    std::vector<std::pair<T*, std::size_t>> m_deadThings;
 };
 
 } // namespace furvm
diff --git a/furvm/src/context.cpp b/furvm/src/context.cpp
index 9cb27e7..131a2be 100644
--- a/furvm/src/context.cpp
+++ b/furvm/src/context.cpp
@@ -4,13 +4,9 @@
 
 namespace furvm {
 
-context::context() {}
+context::context()
+  : m_thingAllocator(m_thingArena) {}
 
-void context::collect() {
-    for (auto& ref : m_things) {
-        if (ref->reference_count() != 0) continue;
-        ref = nullptr;
-    }
-}
+void context::collect() {}
 
 } // namespace furvm
diff --git a/furvm/src/executor.cpp b/furvm/src/executor.cpp
index 2f7cf63..86b99d0 100644
--- a/furvm/src/executor.cpp
+++ b/furvm/src/executor.cpp
@@ -28,21 +28,14 @@ struct executor::frame executor::frame() const {
     return m_frames.top();
 }
 
-void executor::push_thing(const thing_h& thing) {
-    (*thing)->add_reference();
-    m_stack.push(thing);
-}
-
-void executor::push_thing(thing_h&& thing) {
-    (*thing)->add_reference();
-    m_stack.push(std::move(thing));
+thing_h executor::push_thing(::furvm::thing<>&& thing) {
+    return m_stack.emplace(m_context->emplace_thing(std::move(thing)));
 }
 
 thing_h executor::pop_thing() {
     if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
     thing_h top = std::move(m_stack.top());
     m_stack.pop();
-    (*top)->remove_reference();
     return top;
 }
 
@@ -54,20 +47,12 @@ thing_h executor::thing() const {
 void executor::store_thing(variable_t variable, const thing_h& thing) {
     auto& frame = m_frames.top();
     frame.variables.resize(variable + 1);
-    if (*frame.variables[variable] != nullptr) {
-        (*frame.variables[variable])->remove_reference();
-    }
     frame.variables[variable] = thing;
-    (*thing)->add_reference();
 }
 
 void executor::store_thing(variable_t variable, thing_h&& thing) {
     auto& frame = m_frames.top();
     frame.variables.resize(variable + 1);
-    if ((*frame.variables[variable]) != nullptr) {
-        (*frame.variables[variable])->remove_reference();
-    }
-    (*thing)->add_reference();
     frame.variables[variable] = std::move(thing);
 }
 
@@ -81,13 +66,11 @@ void executor::step() {
 
     struct frame& frame = m_frames.top();
 
-    instruction_t instr = static_cast<instruction_t>((*frame.mod)->byte(frame.position++));
+    instruction_t instr = static_cast<instruction_t>((*frame.mod).byte(frame.position++));
     switch (instr) {
     case instruction_t::NoOperation: break;
     case instruction_t::PushB2I: {
-        auto thing        = m_context->emplace_thing(thing_t::Int32);
-        (*thing)->int32() = (*frame.mod)->byte(frame.position++);
-        push_thing(std::move(thing));
+        push_thing({ thing_t::Int32, m_context->m_thingAllocator })->int32() = frame.mod->byte(frame.position++);
     } break;
     case instruction_t::Drop: {
         pop_thing();
@@ -96,81 +79,81 @@ void executor::step() {
         push_thing(thing());
     } break;
     case instruction_t::Clone: {
-        push_thing(std::move(thing::clone(m_context, thing())));
+        push_thing(std::move(thing()->clone()));
     } break;
     case instruction_t::Add: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->add(m_context, rhs));
+        push_thing(lhs->add(*rhs));
     } break;
     case instruction_t::Sub: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->sub(m_context, rhs));
+        push_thing(lhs->sub(*rhs));
     } break;
     case instruction_t::Mul: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->mul(m_context, rhs));
+        push_thing(lhs->mul(*rhs));
     } break;
     case instruction_t::Div: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->div(m_context, rhs));
+        push_thing(lhs->div(*rhs));
     } break;
     case instruction_t::Mod: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->mod(m_context, rhs));
+        push_thing(lhs->mod(*rhs));
     } break;
     case instruction_t::Equals: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->equals(m_context, rhs));
+        push_thing(lhs->equals(*rhs));
     } break;
     case instruction_t::NotEquals: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->not_equals(m_context, rhs));
+        push_thing(lhs->not_equals(*rhs));
     } break;
     case instruction_t::LessThan: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->less_than(m_context, rhs));
+        push_thing(lhs->less_than(*rhs));
     } break;
     case instruction_t::GreaterThan: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->greater_than(m_context, rhs));
+        push_thing(lhs->greater_than(*rhs));
     } break;
     case instruction_t::LessEqual: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->less_equals(m_context, rhs));
+        push_thing(lhs->less_equals(*rhs));
     } break;
     case instruction_t::GreaterEqual: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing((*lhs)->greater_equals(m_context, rhs));
+        push_thing(lhs->greater_equals(*rhs));
     } break;
     case instruction_t::Load: {
-        variable_t variable = static_cast<std::uint16_t>((*frame.mod)->byte(frame.position)) |
-                              (static_cast<std::uint16_t>((*frame.mod)->byte(frame.position + 1)) << 8);
+        variable_t variable = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
+                              (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
         frame.position     += 2;
         push_thing(load_thing(variable));
     } break;
     case instruction_t::Store: {
-        variable_t variable = static_cast<std::uint16_t>((*frame.mod)->byte(frame.position)) |
-                              (static_cast<std::uint16_t>((*frame.mod)->byte(frame.position + 1)) << 8);
+        variable_t variable = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
+                              (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
         frame.position     += 2;
         store_thing(variable, std::move(pop_thing()));
     } break;
     case instruction_t::Call: {
-        function_id funcId = static_cast<std::uint16_t>((*frame.mod)->byte(frame.position)) |
-                             (static_cast<std::uint16_t>((*frame.mod)->byte(frame.position + 1)) << 8);
+        function_id funcId = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
+                             (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
         frame.position    += 2;
 
-        const function_h& function = (*frame.mod)->function_at(funcId);
+        const function_h& function = frame.mod->function_at(funcId);
         switch (function->type()) {
         case function_t::Normal: push_frame(frame.mod, function); break;
         case function_t::Native: function->native()(*this); break;
@@ -182,12 +165,12 @@ void executor::step() {
         }
     } break;
     case instruction_t::Jump: {
-        frame.position += (*frame.mod)->byte(frame.position++);
+        frame.position += frame.mod->byte(frame.position++);
     } break;
     case instruction_t::JumpNotZero: {
-        byte offset = (*frame.mod)->byte(frame.position++);
+        byte offset = frame.mod->byte(frame.position++);
         auto cond   = pop_thing();
-        if ((*cond)->int32() != 0) frame.position += offset;
+        if (cond->int32() != 0) frame.position += offset;
     } break;
     case instruction_t::Return: {
         pop_frame();
diff --git a/furvm/src/main.cpp b/furvm/src/main.cpp
index ebf38e8..724aea9 100644
--- a/furvm/src/main.cpp
+++ b/furvm/src/main.cpp
@@ -5,6 +5,7 @@
 #include "furvm/function.hpp"
 #include "furvm/fwd.hpp"
 #include "furvm/instruction.hpp"
+#include "furvm/module.hpp"
 #include "furvm/serializer.hpp"
 #include "furvm/thing.hpp"
 
@@ -26,7 +27,7 @@ int main(void) {
     auto context = std::make_shared<furvm::context>();
 
     furvm::mod_h      mainModule = context->emplace_module("main", s_bytecode.begin(), s_bytecode.end());
-    furvm::function_h mainFunc   = (*mainModule)->emplace_function("main", 0);
+    furvm::function_h mainFunc   = mainModule->emplace_function("main", 0);
 
     furvm::executor_h executor = context->emplace_executor(context);
     executor->push_frame(mainModule, mainFunc);
diff --git a/furvm/src/serializer.cpp b/furvm/src/serializer.cpp
index 9825766..c07cf80 100644
--- a/furvm/src/serializer.cpp
+++ b/furvm/src/serializer.cpp
@@ -6,7 +6,6 @@
 
 #include <istream>
 #include <ostream>
-#include <stdexcept>
 
 namespace furvm {
 
@@ -68,32 +67,32 @@ static inline void read_u8(std::istream& is, std::uint8_t& value) {
 }
 
 bool serializer::serialize_module(std::ostream& os, const mod_p& mod) {
-    os.write(reinterpret_cast<const char*>(MODULE_MAGIC), sizeof(MODULE_MAGIC));
-    write_u32(os, VERSION);
+    // os.write(reinterpret_cast<const char*>(MODULE_MAGIC), sizeof(MODULE_MAGIC));
+    // write_u32(os, VERSION);
 
-    write_u32(os, mod->m_functions.size());
-    for (function_id id = 0; id < static_cast<function_id>(mod->m_functions.size()); ++id) {
-        const auto& func = mod->function_at(id);
-        write_u16(os, id);
-        write_u8(os, static_cast<std::uint8_t>(func->type()));
-        switch (func->type()) {
-        case function_t::Normal: {
-            write_u64(os, func->position());
-        } break;
-        case function_t::Native: {
-            // TODO: Replace with a reference to the function's name from constant pool
-            throw std::runtime_error("cannot serialize native functions yet");
-        } break;
-        case function_t::Import: {
-            // TODO: Replace with a reference to the module's and function's name from constant pool
-            throw std::runtime_error("cannot serialize import functions yet");
-        } break;
-        }
-    }
+    // write_u32(os, mod->m_functions.size());
+    // for (function_id id = 0; id < static_cast<function_id>(mod->m_functions.size()); ++id) {
+    // const auto& func = mod->function_at(id);
+    // write_u16(os, id);
+    // write_u8(os, static_cast<std::uint8_t>(func->type()));
+    // switch (func->type()) {
+    // case function_t::Normal: {
+    // write_u64(os, func->position());
+    // } break;
+    // case function_t::Native: {
+    // // TODO: Replace with a reference to the function's name from constant pool
+    // throw std::runtime_error("cannot serialize native functions yet");
+    // } break;
+    // case function_t::Import: {
+    // // TODO: Replace with a reference to the module's and function's name from constant pool
+    // throw std::runtime_error("cannot serialize import functions yet");
+    // } break;
+    // }
+    // }
 
-    write_u64(os, mod->m_bytecode.size());
-    os.write(reinterpret_cast<const char*>(mod->m_bytecode.data()),
-        static_cast<std::streamsize>(mod->m_bytecode.size()));
+    // write_u64(os, mod->m_bytecode.size());
+    // os.write(reinterpret_cast<const char*>(mod->m_bytecode.data()),
+    // static_cast<std::streamsize>(mod->m_bytecode.size()));
 
     return false;
 }
diff --git a/furvm/src/thing.cpp b/furvm/src/thing.cpp
deleted file mode 100644
index 8cd4f80..0000000
--- a/furvm/src/thing.cpp
+++ /dev/null
@@ -1,228 +0,0 @@
-// NOLINTBEGIN(cppcoreguidelines-no-malloc)
-
-#include "furvm/thing.hpp"
-
-#include "furvm/context.hpp" // IWYU pragma: keep
-
-#include <cstdlib>
-#include <cstring>
-#include <stdexcept>
-
-namespace furvm {
-
-std::size_t thing_type_size(thing_t type) {
-    switch (type) {
-    case thing_t::Int32: return 4;
-    }
-    return 0;
-}
-
-thing::thing(thing_t type)
-  : m_type(type) {
-    std::size_t size = thing_type_size(type);
-    byte*       data = new byte[size];
-    if (data == nullptr) throw std::runtime_error("failed to allocate data for new thing");
-    std::memcpy(data, &type, sizeof(type));
-    m_data = data + sizeof(type);
-
-    switch (m_type) {
-    // Primitives are zero-initialized.
-    default:
-    case thing_t::Int32: std::memset(m_data, 0, size);
-    }
-}
-
-thing::thing(thing_t type, void* data)
-  : m_type(type), m_ownData(false) {
-    std::size_t size = thing_type_size(type);
-    if (data == nullptr) throw std::runtime_error("failed to allocate data for new thing");
-    std::memcpy(data, &type, sizeof(type));
-    m_data = static_cast<char*>(data) + sizeof(type);
-
-    switch (m_type) {
-    // Primitives are zero-initialized.
-    default:
-    case thing_t::Int32: std::memset(m_data, 0, size);
-    }
-}
-
-thing::~thing() {
-    switch (m_type) {
-    // Primitives are not destructed.
-    default:
-    case thing_t::Int32: break;
-    }
-
-    if (m_ownData) delete[] static_cast<char*>(m_data);
-}
-
-thing::thing(thing&& other) noexcept
-  : m_type(other.m_type), m_refCount(other.m_refCount), m_data(other.m_data) {
-    other.m_type     = {};
-    other.m_ownData  = false;
-    other.m_refCount = {};
-    other.m_data     = nullptr;
-}
-
-thing& thing::operator=(thing&& other) noexcept {
-    if (this == &other) return *this;
-    m_type     = other.m_type;
-    m_refCount = other.m_refCount;
-    m_data     = other.m_data;
-
-    other.m_type     = {};
-    other.m_refCount = {};
-    other.m_data     = nullptr;
-    return *this;
-}
-
-static constexpr std::uint16_t thing_type_pair(thing_t lhs, thing_t rhs) {
-    return (static_cast<std::uint16_t>(lhs) << 8) | static_cast<std::uint16_t>(rhs);
-}
-
-thing_h thing::clone(const context_p& context, const thing_h& thing) {
-    auto th = context->emplace_thing((*thing)->m_type);
-    switch ((*thing)->m_type) {
-    // Primitives
-    default: {
-        memcpy((*th)->m_data, (*thing)->m_data, thing_type_size((*thing)->m_type));
-    }
-    }
-
-    return std::move(th);
-}
-
-std::int32_t& thing::int32() {
-    if (m_type != thing_t::Int32) throw bad_thing_access();
-    return *static_cast<std::int32_t*>(m_data);
-}
-
-const std::int32_t& thing::int32() const {
-    if (m_type != thing_t::Int32) throw bad_thing_access();
-    return *static_cast<std::int32_t*>(m_data);
-}
-
-thing_h thing::add(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = int32() + (*rhs)->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::sub(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = int32() - (*rhs)->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::mul(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = int32() * (*rhs)->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::div(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = int32() / (*rhs)->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::mod(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = int32() % (*rhs)->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::equals(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() == (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::not_equals(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() != (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::less_than(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() < (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::greater_than(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() > (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::less_equals(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() <= (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-thing_h thing::greater_equals(const context_p& context, const thing_h& rhs) const {
-    switch (thing_type_pair(m_type, (*rhs)->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        thing_h res     = context->emplace_thing(thing_t::Int32);
-        (*res)->int32() = static_cast<std::int32_t>(int32() >= (*rhs)->int32());
-        return res;
-    }
-    default: throw std::runtime_error("unreachable");
-    }
-}
-
-} // namespace furvm
-
-// NOLINTEND(cppcoreguidelines-no-malloc)