diff --git a/src/collector.cpp b/src/collector.cpp
new file mode 100644
index 0000000..df66db2
--- /dev/null
+++ b/src/collector.cpp
@@ -0,0 +1,251 @@
+#include <iostream>
+
+/* Requires the mapbox header-only variant found at
+   https://github.com/mapbox/variant
+
+   Compiles with: 
+   clang++ -std=c++14 -I./include/ -o collector collector.cpp
+   …  or
+   g++ -std=c++1y -I./include/ -g -o collector collector.cpp
+   … where 'include' has the variant headers.
+
+   clang version 3.9.1-svn288847-1~exp1 (branches/release_39)
+   g++ version (Ubuntu 4.8.5-2ubuntu1~14.04.1) 4.8.5
+
+*/
+#include <mapbox/variant.hpp>
+
+#define MAX_STACK 256
+#define MAX_BARRIER 8
+
+void my_assert(int condition, const char* message) {
+  if (!condition) {
+    std::cout << message << std::endl;
+    exit(1);
+  }
+}
+
+/* An implementation of Bob Nystrom's "Baby's First Garbage Collector"
+   http://journal.stuffwithstuff.com/2013/12/08/babys-first-garbage-collector/,
+   only in C++, and with some educational stuff along the way about
+   the new Variant (automagical discriminated unions) coming in
+   Libstdc++ version 4, part of the C++ 2017 standard.
+*/
+
+class Object {
+public:
+  unsigned char marked;
+  Object *next;
+  Object(int v): marked(0), value(v) {}
+  Object(Object* head, Object* tail): marked(0), value(Pair(head, tail)) {}
+
+  class Pair {
+  public:
+    Pair(Object* h, Object* t): head(h), tail(t) {};
+    Object* head;
+    Object* tail;
+  };
+
+  /* This is mostly an exploration of a discriminated union, and
+     making one work in the context of a primitive but functional
+     garbage collector. */
+  mapbox::util::variant<int, Pair> value;
+};
+
+class VM {
+public:
+  /* Imagine my surprise when I learned that clang doesn't bother to
+     zero out memory allocated on the threadstack. */
+  VM(): stackSize(0), numObjects(0), maxObjects(MAX_BARRIER), root(NULL) {};
+  
+  Object* pop() {
+    my_assert(stackSize > 0, "Stack underflow!");
+    return stack[--stackSize];
+  }
+
+  /* This is basically the interface for a very primitive reverse
+     polish notation calculator of some kind.  A garbage-collected
+     Forth interpreter, perhaps. */
+
+  Object* push(int v) {
+    return _push(insert(new Object(v)));
+  }
+  
+  Object* push() {
+    return _push(insert(new Object(pop(), pop())));
+  }
+
+  /* Lambda-style visitors, enabling descent. */
+  void mark(Object *o) {
+    auto marker = mapbox::util::make_visitor(
+        [this](int) {},
+        [this](Object::Pair p) {
+          this->mark(p.head);
+          this->mark(p.tail);
+    });
+    
+    if (o->marked) {
+      return;
+    }
+
+    o->marked = 1;
+    return mapbox::util::apply_visitor(marker, o->value);
+  }
+
+  /* So named because each scope resembles a collection of objects
+     leading horizontally from the vertical stack, creating a spine. */
+  void markSpine() {
+    for(auto i = 0; i < stackSize; i++) {
+      mark(stack[i]);
+    }
+  }
+
+  void collect() {
+    int num = numObjects;
+    markSpine();
+    sweep();
+    maxObjects = numObjects * 2;
+#ifdef DEBUG
+    std::cout << "Collected " << (num - numObjects) << " objects, "
+              << numObjects << " remain." << std::endl;
+#endif
+  }
+
+  /* The saddest fact: I went with using NULL as our end-of-stack
+     discriminator rather than something higher-level, like an
+     Optional or Either-variant, because to use those I'd have to
+     user recursion to sweep the interpreter's stack, which means
+     I'm at the mercy of the C stack, complete with the cost of the
+     unwind at the end.  Bummer. */
+
+  /* I look at this and ask, WWHSD?  What Would Herb Sutter Do? */
+  
+  void sweep() {
+    Object** o = &root;
+    while(*o) {
+      if (!(*o)->marked) {
+        Object* unreached = *o;
+        *o = unreached->next;
+        numObjects--;
+        delete unreached;
+      } else {
+        (*o)->marked = 0;
+        o = &(*o)->next;
+      }
+    }
+  }
+      
+  int numObjects;
+  
+private:
+
+  /* Heh.  Typo, "Stark overflow."  I'll just leave Tony right there anyway... */
+  Object* _push(Object *o) {
+    my_assert(stackSize < MAX_STACK, "Stark overflow");
+    stack[stackSize++] = o;
+    return o;
+  }
+  
+  Object* insert(Object *o) {
+    if (numObjects >= maxObjects) {
+      collect();
+    }
+    
+    o->marked = 0;
+    o->next = root;
+    root = o;
+    numObjects++;
+    return o;
+  }
+    
+  Object* stack[MAX_STACK];
+  Object* root;
+  int stackSize;
+  int maxObjects;
+};
+
+
+void test1() {
+  std::cout << "Test 1: Objects on stack are preserved." << std::endl;
+  VM vm;
+  vm.push(1);
+  vm.push(2);
+  vm.collect();
+  my_assert(vm.numObjects == 2, "Should have preserved objects.");
+}
+
+void test2() {
+  std::cout << "Test 2: Unreached objects are collected." << std::endl;
+  VM vm;
+  vm.push(1);
+  vm.push(2);
+  vm.pop();
+  vm.pop();
+  vm.collect();
+  my_assert(vm.numObjects == 0, "Should have collected objects.");
+
+}
+    
+void test3() {
+  std::cout << "Test 3: Reach nested objects." << std::endl;
+  VM vm;
+  vm.push(1);
+  vm.push(2);
+  vm.push();
+  vm.push(3);
+  vm.push(4);
+  vm.push();
+  vm.push();
+  vm.collect();
+  my_assert(vm.numObjects == 7, "Should have reached objects.");
+}
+
+void test4() {
+  std::cout << "Test 4: Handle cycles." << std::endl;
+  VM vm;
+  vm.push(1);
+  vm.push(2);
+  Object* a = vm.push();
+  vm.push(3);
+  vm.push(4);
+  Object* b = vm.push();
+
+  /* Constructor-based variant visitor. */
+  struct tail_setter {
+    Object* tail;
+    tail_setter(Object *t) : tail(t) {}
+    inline void operator()(int &i) {}
+    inline void operator()(Object::Pair &p) { p.tail = tail; }
+  };
+  
+  /* Set up a cycle, and also make 2 and 4 unreachable and collectible. */
+  mapbox::util::apply_visitor(tail_setter(b), a->value);
+  mapbox::util::apply_visitor(tail_setter(a), b->value);
+  vm.collect();
+  my_assert(vm.numObjects == 4, "Should have collected objects.");
+}
+
+void perfTest() {
+  std::cout << "Performance Test." << std::endl;
+  VM vm;
+
+  for (int i = 0; i < 1000; i++) {
+    for (int j = 0; j < 20; j++) {
+      vm.push(i);
+    }
+
+    for (int k = 0; k < 20; k++) {
+      vm.pop();
+    }
+  }
+}
+
+int main(int argc, const char * argv[]) {
+  test1();
+  test2();
+  test3();
+  test4();
+  perfTest();
+
+  return 0;
+}
diff --git a/src/include/mapbox/optional.hpp b/src/include/mapbox/optional.hpp
new file mode 100644
index 0000000..d84705c
--- /dev/null
+++ b/src/include/mapbox/optional.hpp
@@ -0,0 +1,74 @@
+#ifndef MAPBOX_UTIL_OPTIONAL_HPP
+#define MAPBOX_UTIL_OPTIONAL_HPP
+
+#pragma message("This implementation of optional is deprecated. See https://github.com/mapbox/variant/issues/64.")
+
+#include <type_traits>
+#include <utility>
+
+#include <mapbox/variant.hpp>
+
+namespace mapbox {
+namespace util {
+
+template <typename T>
+class optional
+{
+    static_assert(!std::is_reference<T>::value, "optional doesn't support references");
+
+    struct none_type
+    {
+    };
+
+    variant<none_type, T> variant_;
+
+public:
+    optional() = default;
+
+    optional(optional const& rhs)
+    {
+        if (this != &rhs)
+        { // protect against invalid self-assignment
+            variant_ = rhs.variant_;
+        }
+    }
+
+    optional(T const& v) { variant_ = v; }
+
+    explicit operator bool() const noexcept { return variant_.template is<T>(); }
+
+    T const& get() const { return variant_.template get<T>(); }
+    T& get() { return variant_.template get<T>(); }
+
+    T const& operator*() const { return this->get(); }
+    T operator*() { return this->get(); }
+
+    optional& operator=(T const& v)
+    {
+        variant_ = v;
+        return *this;
+    }
+
+    optional& operator=(optional const& rhs)
+    {
+        if (this != &rhs)
+        {
+            variant_ = rhs.variant_;
+        }
+        return *this;
+    }
+
+    template <typename... Args>
+    void emplace(Args&&... args)
+    {
+        variant_ = T{std::forward<Args>(args)...};
+    }
+
+    void reset() { variant_ = none_type{}; }
+
+}; // class optional
+
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_OPTIONAL_HPP
diff --git a/src/include/mapbox/recursive_wrapper.hpp b/src/include/mapbox/recursive_wrapper.hpp
new file mode 100644
index 0000000..4ffcbd7
--- /dev/null
+++ b/src/include/mapbox/recursive_wrapper.hpp
@@ -0,0 +1,122 @@
+#ifndef MAPBOX_UTIL_RECURSIVE_WRAPPER_HPP
+#define MAPBOX_UTIL_RECURSIVE_WRAPPER_HPP
+
+// Based on variant/recursive_wrapper.hpp from boost.
+//
+// Original license:
+//
+// Copyright (c) 2002-2003
+// Eric Friedman, Itay Maman
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <cassert>
+#include <utility>
+
+namespace mapbox {
+namespace util {
+
+template <typename T>
+class recursive_wrapper
+{
+
+    T* p_;
+
+    void assign(T const& rhs)
+    {
+        this->get() = rhs;
+    }
+
+public:
+    using type = T;
+
+    /**
+     * Default constructor default initializes the internally stored value.
+     * For POD types this means nothing is done and the storage is
+     * uninitialized.
+     *
+     * @throws std::bad_alloc if there is insufficient memory for an object
+     *         of type T.
+     * @throws any exception thrown by the default constructur of T.
+     */
+    recursive_wrapper()
+        : p_(new T){}
+
+    ~recursive_wrapper() noexcept { delete p_; }
+
+    recursive_wrapper(recursive_wrapper const& operand)
+        : p_(new T(operand.get())) {}
+
+    recursive_wrapper(T const& operand)
+        : p_(new T(operand)) {}
+
+    recursive_wrapper(recursive_wrapper&& operand)
+        : p_(new T(std::move(operand.get()))) {}
+
+    recursive_wrapper(T&& operand)
+        : p_(new T(std::move(operand))) {}
+
+    inline recursive_wrapper& operator=(recursive_wrapper const& rhs)
+    {
+        assign(rhs.get());
+        return *this;
+    }
+
+    inline recursive_wrapper& operator=(T const& rhs)
+    {
+        assign(rhs);
+        return *this;
+    }
+
+    inline void swap(recursive_wrapper& operand) noexcept
+    {
+        T* temp = operand.p_;
+        operand.p_ = p_;
+        p_ = temp;
+    }
+
+    recursive_wrapper& operator=(recursive_wrapper&& rhs) noexcept
+    {
+        swap(rhs);
+        return *this;
+    }
+
+    recursive_wrapper& operator=(T&& rhs)
+    {
+        get() = std::move(rhs);
+        return *this;
+    }
+
+    T& get()
+    {
+        assert(p_);
+        return *get_pointer();
+    }
+
+    T const& get() const
+    {
+        assert(p_);
+        return *get_pointer();
+    }
+
+    T* get_pointer() { return p_; }
+
+    const T* get_pointer() const { return p_; }
+
+    operator T const&() const { return this->get(); }
+
+    operator T&() { return this->get(); }
+
+}; // class recursive_wrapper
+
+template <typename T>
+inline void swap(recursive_wrapper<T>& lhs, recursive_wrapper<T>& rhs) noexcept
+{
+    lhs.swap(rhs);
+}
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_RECURSIVE_WRAPPER_HPP
diff --git a/src/include/mapbox/variant.hpp b/src/include/mapbox/variant.hpp
new file mode 100644
index 0000000..fb0f77e
--- /dev/null
+++ b/src/include/mapbox/variant.hpp
@@ -0,0 +1,1013 @@
+#ifndef MAPBOX_UTIL_VARIANT_HPP
+#define MAPBOX_UTIL_VARIANT_HPP
+
+#include <cassert>
+#include <cstddef>   // size_t
+#include <new>       // operator new
+#include <stdexcept> // runtime_error
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <typeinfo>
+#include <utility>
+#include <functional>
+
+#include <mapbox/recursive_wrapper.hpp>
+#include <mapbox/variant_visitor.hpp>
+
+// clang-format off
+// [[deprecated]] is only available in C++14, use this for the time being
+#if __cplusplus <= 201103L
+# ifdef __GNUC__
+#  define MAPBOX_VARIANT_DEPRECATED __attribute__((deprecated))
+# elif defined(_MSC_VER)
+#  define MAPBOX_VARIANT_DEPRECATED __declspec(deprecated)
+# else
+#  define MAPBOX_VARIANT_DEPRECATED
+# endif
+#else
+#  define MAPBOX_VARIANT_DEPRECATED [[deprecated]]
+#endif
+
+
+#ifdef _MSC_VER
+// https://msdn.microsoft.com/en-us/library/bw1hbe6y.aspx
+# ifdef NDEBUG
+#  define VARIANT_INLINE __forceinline
+# else
+#  define VARIANT_INLINE //__declspec(noinline)
+# endif
+#else
+# ifdef NDEBUG
+#  define VARIANT_INLINE //inline __attribute__((always_inline))
+# else
+#  define VARIANT_INLINE __attribute__((noinline))
+# endif
+#endif
+// clang-format on
+
+// Exceptions
+#if defined( __EXCEPTIONS) || defined( _MSC_VER)
+#define HAS_EXCEPTIONS
+#endif
+
+#define VARIANT_MAJOR_VERSION 1
+#define VARIANT_MINOR_VERSION 1
+#define VARIANT_PATCH_VERSION 0
+
+#define VARIANT_VERSION (VARIANT_MAJOR_VERSION * 100000) + (VARIANT_MINOR_VERSION * 100) + (VARIANT_PATCH_VERSION)
+
+namespace mapbox {
+namespace util {
+
+// XXX This should derive from std::logic_error instead of std::runtime_error.
+//     See https://github.com/mapbox/variant/issues/48 for details.
+class bad_variant_access : public std::runtime_error
+{
+
+public:
+    explicit bad_variant_access(const std::string& what_arg)
+        : runtime_error(what_arg) {}
+
+    explicit bad_variant_access(const char* what_arg)
+        : runtime_error(what_arg) {}
+
+}; // class bad_variant_access
+
+template <typename R = void>
+struct MAPBOX_VARIANT_DEPRECATED static_visitor
+{
+    using result_type = R;
+
+protected:
+    static_visitor() {}
+    ~static_visitor() {}
+};
+
+namespace detail {
+
+static constexpr std::size_t invalid_value = std::size_t(-1);
+
+template <typename T, typename... Types>
+struct direct_type;
+
+template <typename T, typename First, typename... Types>
+struct direct_type<T, First, Types...>
+{
+    static constexpr std::size_t index = std::is_same<T, First>::value
+        ? sizeof...(Types)
+        : direct_type<T, Types...>::index;
+};
+
+template <typename T>
+struct direct_type<T>
+{
+    static constexpr std::size_t index = invalid_value;
+};
+
+#if __cpp_lib_logical_traits >= 201510L
+
+using std::disjunction;
+
+#else
+
+template <typename...>
+struct disjunction : std::false_type {};
+
+template <typename B1>
+struct disjunction<B1> : B1 {};
+
+template <typename B1, typename B2>
+struct disjunction<B1, B2> : std::conditional<B1::value, B1, B2>::type {};
+
+template <typename B1, typename... Bs>
+struct disjunction<B1, Bs...> : std::conditional<B1::value, B1, disjunction<Bs...>>::type {};
+
+#endif
+
+template <typename T, typename... Types>
+struct convertible_type;
+
+template <typename T, typename First, typename... Types>
+struct convertible_type<T, First, Types...>
+{
+    static constexpr std::size_t index = std::is_convertible<T, First>::value
+        ? disjunction<std::is_convertible<T, Types>...>::value ? invalid_value : sizeof...(Types)
+        : convertible_type<T, Types...>::index;
+};
+
+template <typename T>
+struct convertible_type<T>
+{
+    static constexpr std::size_t index = invalid_value;
+};
+
+template <typename T, typename... Types>
+struct value_traits
+{
+    using value_type = typename std::remove_const<typename std::remove_reference<T>::type>::type;
+    static constexpr std::size_t direct_index = direct_type<value_type, Types...>::index;
+    static constexpr bool is_direct = direct_index != invalid_value;
+    static constexpr std::size_t index = is_direct ? direct_index : convertible_type<value_type, Types...>::index;
+    static constexpr bool is_valid = index != invalid_value;
+    static constexpr std::size_t tindex = is_valid ? sizeof...(Types)-index : 0;
+    using target_type = typename std::tuple_element<tindex, std::tuple<void, Types...>>::type;
+};
+
+template <typename T, typename R = void>
+struct enable_if_type
+{
+    using type = R;
+};
+
+template <typename F, typename V, typename Enable = void>
+struct result_of_unary_visit
+{
+    using type = typename std::result_of<F(V&)>::type;
+};
+
+template <typename F, typename V>
+struct result_of_unary_visit<F, V, typename enable_if_type<typename F::result_type>::type>
+{
+    using type = typename F::result_type;
+};
+
+template <typename F, typename V, typename Enable = void>
+struct result_of_binary_visit
+{
+    using type = typename std::result_of<F(V&, V&)>::type;
+};
+
+template <typename F, typename V>
+struct result_of_binary_visit<F, V, typename enable_if_type<typename F::result_type>::type>
+{
+    using type = typename F::result_type;
+};
+
+template <std::size_t arg1, std::size_t... others>
+struct static_max;
+
+template <std::size_t arg>
+struct static_max<arg>
+{
+    static const std::size_t value = arg;
+};
+
+template <std::size_t arg1, std::size_t arg2, std::size_t... others>
+struct static_max<arg1, arg2, others...>
+{
+    static const std::size_t value = arg1 >= arg2 ? static_max<arg1, others...>::value : static_max<arg2, others...>::value;
+};
+
+template <typename... Types>
+struct variant_helper;
+
+template <typename T, typename... Types>
+struct variant_helper<T, Types...>
+{
+    VARIANT_INLINE static void destroy(const std::size_t type_index, void* data)
+    {
+        if (type_index == sizeof...(Types))
+        {
+            reinterpret_cast<T*>(data)->~T();
+        }
+        else
+        {
+            variant_helper<Types...>::destroy(type_index, data);
+        }
+    }
+
+    VARIANT_INLINE static void move(const std::size_t old_type_index, void* old_value, void* new_value)
+    {
+        if (old_type_index == sizeof...(Types))
+        {
+            new (new_value) T(std::move(*reinterpret_cast<T*>(old_value)));
+        }
+        else
+        {
+            variant_helper<Types...>::move(old_type_index, old_value, new_value);
+        }
+    }
+
+    VARIANT_INLINE static void copy(const std::size_t old_type_index, const void* old_value, void* new_value)
+    {
+        if (old_type_index == sizeof...(Types))
+        {
+            new (new_value) T(*reinterpret_cast<const T*>(old_value));
+        }
+        else
+        {
+            variant_helper<Types...>::copy(old_type_index, old_value, new_value);
+        }
+    }
+};
+
+template <>
+struct variant_helper<>
+{
+    VARIANT_INLINE static void destroy(const std::size_t, void*) {}
+    VARIANT_INLINE static void move(const std::size_t, void*, void*) {}
+    VARIANT_INLINE static void copy(const std::size_t, const void*, void*) {}
+};
+
+template <typename T>
+struct unwrapper
+{
+    static T const& apply_const(T const& obj) { return obj; }
+    static T& apply(T& obj) { return obj; }
+};
+
+template <typename T>
+struct unwrapper<recursive_wrapper<T>>
+{
+    static auto apply_const(recursive_wrapper<T> const& obj)
+        -> typename recursive_wrapper<T>::type const&
+    {
+        return obj.get();
+    }
+    static auto apply(recursive_wrapper<T>& obj)
+        -> typename recursive_wrapper<T>::type&
+    {
+        return obj.get();
+    }
+};
+
+template <typename T>
+struct unwrapper<std::reference_wrapper<T>>
+{
+    static auto apply_const(std::reference_wrapper<T> const& obj)
+        -> typename std::reference_wrapper<T>::type const&
+    {
+        return obj.get();
+    }
+    static auto apply(std::reference_wrapper<T>& obj)
+        -> typename std::reference_wrapper<T>::type&
+    {
+        return obj.get();
+    }
+};
+
+template <typename F, typename V, typename R, typename... Types>
+struct dispatcher;
+
+template <typename F, typename V, typename R, typename T, typename... Types>
+struct dispatcher<F, V, R, T, Types...>
+{
+    VARIANT_INLINE static R apply_const(V const& v, F&& f)
+    {
+        if (v.template is<T>())
+        {
+            return f(unwrapper<T>::apply_const(v.template get_unchecked<T>()));
+        }
+        else
+        {
+            return dispatcher<F, V, R, Types...>::apply_const(v, std::forward<F>(f));
+        }
+    }
+
+    VARIANT_INLINE static R apply(V& v, F&& f)
+    {
+        if (v.template is<T>())
+        {
+            return f(unwrapper<T>::apply(v.template get_unchecked<T>()));
+        }
+        else
+        {
+            return dispatcher<F, V, R, Types...>::apply(v, std::forward<F>(f));
+        }
+    }
+};
+
+template <typename F, typename V, typename R, typename T>
+struct dispatcher<F, V, R, T>
+{
+    VARIANT_INLINE static R apply_const(V const& v, F&& f)
+    {
+        return f(unwrapper<T>::apply_const(v.template get_unchecked<T>()));
+    }
+
+    VARIANT_INLINE static R apply(V& v, F&& f)
+    {
+        return f(unwrapper<T>::apply(v.template get_unchecked<T>()));
+    }
+};
+
+template <typename F, typename V, typename R, typename T, typename... Types>
+struct binary_dispatcher_rhs;
+
+template <typename F, typename V, typename R, typename T0, typename T1, typename... Types>
+struct binary_dispatcher_rhs<F, V, R, T0, T1, Types...>
+{
+    VARIANT_INLINE static R apply_const(V const& lhs, V const& rhs, F&& f)
+    {
+        if (rhs.template is<T1>()) // call binary functor
+        {
+            return f(unwrapper<T0>::apply_const(lhs.template get_unchecked<T0>()),
+                     unwrapper<T1>::apply_const(rhs.template get_unchecked<T1>()));
+        }
+        else
+        {
+            return binary_dispatcher_rhs<F, V, R, T0, Types...>::apply_const(lhs, rhs, std::forward<F>(f));
+        }
+    }
+
+    VARIANT_INLINE static R apply(V& lhs, V& rhs, F&& f)
+    {
+        if (rhs.template is<T1>()) // call binary functor
+        {
+            return f(unwrapper<T0>::apply(lhs.template get_unchecked<T0>()),
+                     unwrapper<T1>::apply(rhs.template get_unchecked<T1>()));
+        }
+        else
+        {
+            return binary_dispatcher_rhs<F, V, R, T0, Types...>::apply(lhs, rhs, std::forward<F>(f));
+        }
+    }
+};
+
+template <typename F, typename V, typename R, typename T0, typename T1>
+struct binary_dispatcher_rhs<F, V, R, T0, T1>
+{
+    VARIANT_INLINE static R apply_const(V const& lhs, V const& rhs, F&& f)
+    {
+        return f(unwrapper<T0>::apply_const(lhs.template get_unchecked<T0>()),
+                 unwrapper<T1>::apply_const(rhs.template get_unchecked<T1>()));
+    }
+
+    VARIANT_INLINE static R apply(V& lhs, V& rhs, F&& f)
+    {
+        return f(unwrapper<T0>::apply(lhs.template get_unchecked<T0>()),
+                 unwrapper<T1>::apply(rhs.template get_unchecked<T1>()));
+    }
+};
+
+template <typename F, typename V, typename R, typename T, typename... Types>
+struct binary_dispatcher_lhs;
+
+template <typename F, typename V, typename R, typename T0, typename T1, typename... Types>
+struct binary_dispatcher_lhs<F, V, R, T0, T1, Types...>
+{
+    VARIANT_INLINE static R apply_const(V const& lhs, V const& rhs, F&& f)
+    {
+        if (lhs.template is<T1>()) // call binary functor
+        {
+            return f(unwrapper<T1>::apply_const(lhs.template get_unchecked<T1>()),
+                     unwrapper<T0>::apply_const(rhs.template get_unchecked<T0>()));
+        }
+        else
+        {
+            return binary_dispatcher_lhs<F, V, R, T0, Types...>::apply_const(lhs, rhs, std::forward<F>(f));
+        }
+    }
+
+    VARIANT_INLINE static R apply(V& lhs, V& rhs, F&& f)
+    {
+        if (lhs.template is<T1>()) // call binary functor
+        {
+            return f(unwrapper<T1>::apply(lhs.template get_unchecked<T1>()),
+                     unwrapper<T0>::apply(rhs.template get_unchecked<T0>()));
+        }
+        else
+        {
+            return binary_dispatcher_lhs<F, V, R, T0, Types...>::apply(lhs, rhs, std::forward<F>(f));
+        }
+    }
+};
+
+template <typename F, typename V, typename R, typename T0, typename T1>
+struct binary_dispatcher_lhs<F, V, R, T0, T1>
+{
+    VARIANT_INLINE static R apply_const(V const& lhs, V const& rhs, F&& f)
+    {
+        return f(unwrapper<T1>::apply_const(lhs.template get_unchecked<T1>()),
+                 unwrapper<T0>::apply_const(rhs.template get_unchecked<T0>()));
+    }
+
+    VARIANT_INLINE static R apply(V& lhs, V& rhs, F&& f)
+    {
+        return f(unwrapper<T1>::apply(lhs.template get_unchecked<T1>()),
+                 unwrapper<T0>::apply(rhs.template get_unchecked<T0>()));
+    }
+};
+
+template <typename F, typename V, typename R, typename... Types>
+struct binary_dispatcher;
+
+template <typename F, typename V, typename R, typename T, typename... Types>
+struct binary_dispatcher<F, V, R, T, Types...>
+{
+    VARIANT_INLINE static R apply_const(V const& v0, V const& v1, F&& f)
+    {
+        if (v0.template is<T>())
+        {
+            if (v1.template is<T>())
+            {
+                return f(unwrapper<T>::apply_const(v0.template get_unchecked<T>()),
+                         unwrapper<T>::apply_const(v1.template get_unchecked<T>())); // call binary functor
+            }
+            else
+            {
+                return binary_dispatcher_rhs<F, V, R, T, Types...>::apply_const(v0, v1, std::forward<F>(f));
+            }
+        }
+        else if (v1.template is<T>())
+        {
+            return binary_dispatcher_lhs<F, V, R, T, Types...>::apply_const(v0, v1, std::forward<F>(f));
+        }
+        return binary_dispatcher<F, V, R, Types...>::apply_const(v0, v1, std::forward<F>(f));
+    }
+
+    VARIANT_INLINE static R apply(V& v0, V& v1, F&& f)
+    {
+        if (v0.template is<T>())
+        {
+            if (v1.template is<T>())
+            {
+                return f(unwrapper<T>::apply(v0.template get_unchecked<T>()),
+                         unwrapper<T>::apply(v1.template get_unchecked<T>())); // call binary functor
+            }
+            else
+            {
+                return binary_dispatcher_rhs<F, V, R, T, Types...>::apply(v0, v1, std::forward<F>(f));
+            }
+        }
+        else if (v1.template is<T>())
+        {
+            return binary_dispatcher_lhs<F, V, R, T, Types...>::apply(v0, v1, std::forward<F>(f));
+        }
+        return binary_dispatcher<F, V, R, Types...>::apply(v0, v1, std::forward<F>(f));
+    }
+};
+
+template <typename F, typename V, typename R, typename T>
+struct binary_dispatcher<F, V, R, T>
+{
+    VARIANT_INLINE static R apply_const(V const& v0, V const& v1, F&& f)
+    {
+        return f(unwrapper<T>::apply_const(v0.template get_unchecked<T>()),
+                 unwrapper<T>::apply_const(v1.template get_unchecked<T>())); // call binary functor
+    }
+
+    VARIANT_INLINE static R apply(V& v0, V& v1, F&& f)
+    {
+        return f(unwrapper<T>::apply(v0.template get_unchecked<T>()),
+                 unwrapper<T>::apply(v1.template get_unchecked<T>())); // call binary functor
+    }
+};
+
+// comparator functors
+struct equal_comp
+{
+    template <typename T>
+    bool operator()(T const& lhs, T const& rhs) const
+    {
+        return lhs == rhs;
+    }
+};
+
+struct less_comp
+{
+    template <typename T>
+    bool operator()(T const& lhs, T const& rhs) const
+    {
+        return lhs < rhs;
+    }
+};
+
+template <typename Variant, typename Comp>
+class comparer
+{
+public:
+    explicit comparer(Variant const& lhs) noexcept
+        : lhs_(lhs) {}
+    comparer& operator=(comparer const&) = delete;
+    // visitor
+    template <typename T>
+    bool operator()(T const& rhs_content) const
+    {
+        T const& lhs_content = lhs_.template get_unchecked<T>();
+        return Comp()(lhs_content, rhs_content);
+    }
+
+private:
+    Variant const& lhs_;
+};
+
+// hashing visitor
+struct hasher
+{
+    template <typename T>
+    std::size_t operator()(const T& hashable) const
+    {
+        return std::hash<T>{}(hashable);
+    }
+};
+
+} // namespace detail
+
+struct no_init
+{
+};
+
+template <typename... Types>
+class variant
+{
+    static_assert(sizeof...(Types) > 0, "Template parameter type list of variant can not be empty");
+    static_assert(!detail::disjunction<std::is_reference<Types>...>::value, "Variant can not hold reference types. Maybe use std::reference_wrapper?");
+
+private:
+    static const std::size_t data_size = detail::static_max<sizeof(Types)...>::value;
+    static const std::size_t data_align = detail::static_max<alignof(Types)...>::value;
+public:
+    struct adapted_variant_tag;
+    using types = std::tuple<Types...>;
+private:
+    using first_type = typename std::tuple_element<0, types>::type;
+    using data_type = typename std::aligned_storage<data_size, data_align>::type;
+    using helper_type = detail::variant_helper<Types...>;
+
+    std::size_t type_index;
+    data_type data;
+
+public:
+    VARIANT_INLINE variant() noexcept(std::is_nothrow_default_constructible<first_type>::value)
+        : type_index(sizeof...(Types)-1)
+    {
+        static_assert(std::is_default_constructible<first_type>::value, "First type in variant must be default constructible to allow default construction of variant");
+        new (&data) first_type();
+    }
+
+    VARIANT_INLINE variant(no_init) noexcept
+        : type_index(detail::invalid_value) {}
+
+    // http://isocpp.org/blog/2012/11/universal-references-in-c11-scott-meyers
+    template <typename T, typename Traits = detail::value_traits<T, Types...>,
+              typename Enable = typename std::enable_if<Traits::is_valid && !std::is_same<variant<Types...>, typename Traits::value_type>::value>::type >
+    VARIANT_INLINE variant(T&& val) noexcept(std::is_nothrow_constructible<typename Traits::target_type, T&&>::value)
+        : type_index(Traits::index)
+    {
+        new (&data) typename Traits::target_type(std::forward<T>(val));
+    }
+
+    VARIANT_INLINE variant(variant<Types...> const& old)
+        : type_index(old.type_index)
+    {
+        helper_type::copy(old.type_index, &old.data, &data);
+    }
+
+    VARIANT_INLINE variant(variant<Types...>&& old) noexcept(std::is_nothrow_move_constructible<types>::value)
+        : type_index(old.type_index)
+    {
+        helper_type::move(old.type_index, &old.data, &data);
+    }
+
+private:
+    VARIANT_INLINE void copy_assign(variant<Types...> const& rhs)
+    {
+        helper_type::destroy(type_index, &data);
+        type_index = detail::invalid_value;
+        helper_type::copy(rhs.type_index, &rhs.data, &data);
+        type_index = rhs.type_index;
+    }
+
+    VARIANT_INLINE void move_assign(variant<Types...>&& rhs)
+    {
+        helper_type::destroy(type_index, &data);
+        type_index = detail::invalid_value;
+        helper_type::move(rhs.type_index, &rhs.data, &data);
+        type_index = rhs.type_index;
+    }
+
+public:
+    VARIANT_INLINE variant<Types...>& operator=(variant<Types...>&& other)
+    {
+        move_assign(std::move(other));
+        return *this;
+    }
+
+    VARIANT_INLINE variant<Types...>& operator=(variant<Types...> const& other)
+    {
+        copy_assign(other);
+        return *this;
+    }
+
+    // conversions
+    // move-assign
+    template <typename T>
+    VARIANT_INLINE variant<Types...>& operator=(T&& rhs) noexcept
+    {
+        variant<Types...> temp(std::forward<T>(rhs));
+        move_assign(std::move(temp));
+        return *this;
+    }
+
+    // copy-assign
+    template <typename T>
+    VARIANT_INLINE variant<Types...>& operator=(T const& rhs)
+    {
+        variant<Types...> temp(rhs);
+        copy_assign(temp);
+        return *this;
+    }
+
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE bool is() const
+    {
+        return type_index == detail::direct_type<T, Types...>::index;
+    }
+
+    template <typename T,typename std::enable_if<
+                         (detail::direct_type<recursive_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE bool is() const
+    {
+        return type_index == detail::direct_type<recursive_wrapper<T>, Types...>::index;
+    }
+
+    VARIANT_INLINE bool valid() const
+    {
+        return type_index != detail::invalid_value;
+    }
+
+    template <typename T, typename... Args>
+    VARIANT_INLINE void set(Args&&... args)
+    {
+        helper_type::destroy(type_index, &data);
+        type_index = detail::invalid_value;
+        new (&data) T(std::forward<Args>(args)...);
+        type_index = detail::direct_type<T, Types...>::index;
+    }
+
+    // get_unchecked<T>()
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get_unchecked()
+    {
+        return *reinterpret_cast<T*>(&data);
+    }
+
+#ifdef HAS_EXCEPTIONS
+    // get<T>()
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get()
+    {
+        if (type_index == detail::direct_type<T, Types...>::index)
+        {
+            return *reinterpret_cast<T*>(&data);
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get_unchecked() const
+    {
+        return *reinterpret_cast<T const*>(&data);
+    }
+
+#ifdef HAS_EXCEPTIONS
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get() const
+    {
+        if (type_index == detail::direct_type<T, Types...>::index)
+        {
+            return *reinterpret_cast<T const*>(&data);
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    // get_unchecked<T>() - T stored as recursive_wrapper<T>
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<recursive_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get_unchecked()
+    {
+        return (*reinterpret_cast<recursive_wrapper<T>*>(&data)).get();
+    }
+
+#ifdef HAS_EXCEPTIONS
+    // get<T>() - T stored as recursive_wrapper<T>
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<recursive_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get()
+    {
+        if (type_index == detail::direct_type<recursive_wrapper<T>, Types...>::index)
+        {
+            return (*reinterpret_cast<recursive_wrapper<T>*>(&data)).get();
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<recursive_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get_unchecked() const
+    {
+        return (*reinterpret_cast<recursive_wrapper<T> const*>(&data)).get();
+    }
+
+#ifdef HAS_EXCEPTIONS
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<recursive_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get() const
+    {
+        if (type_index == detail::direct_type<recursive_wrapper<T>, Types...>::index)
+        {
+            return (*reinterpret_cast<recursive_wrapper<T> const*>(&data)).get();
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    // get_unchecked<T>() - T stored as std::reference_wrapper<T>
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<std::reference_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get_unchecked()
+    {
+        return (*reinterpret_cast<std::reference_wrapper<T>*>(&data)).get();
+    }
+
+#ifdef HAS_EXCEPTIONS
+    // get<T>() - T stored as std::reference_wrapper<T>
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<std::reference_wrapper<T>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T& get()
+    {
+        if (type_index == detail::direct_type<std::reference_wrapper<T>, Types...>::index)
+        {
+            return (*reinterpret_cast<std::reference_wrapper<T>*>(&data)).get();
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<std::reference_wrapper<T const>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get_unchecked() const
+    {
+        return (*reinterpret_cast<std::reference_wrapper<T const> const*>(&data)).get();
+    }
+
+#ifdef HAS_EXCEPTIONS
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<std::reference_wrapper<T const>, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE T const& get() const
+    {
+        if (type_index == detail::direct_type<std::reference_wrapper<T const>, Types...>::index)
+        {
+            return (*reinterpret_cast<std::reference_wrapper<T const> const*>(&data)).get();
+        }
+        else
+        {
+            throw bad_variant_access("in get<T>()");
+        }
+    }
+#endif
+
+    // This function is deprecated because it returns an internal index field.
+    // Use which() instead.
+    MAPBOX_VARIANT_DEPRECATED VARIANT_INLINE std::size_t get_type_index() const
+    {
+        return type_index;
+    }
+
+    VARIANT_INLINE int which() const noexcept
+    {
+        return static_cast<int>(sizeof...(Types)-type_index - 1);
+    }
+
+    template <typename T, typename std::enable_if<
+                          (detail::direct_type<T, Types...>::index != detail::invalid_value)>::type* = nullptr>
+    VARIANT_INLINE static constexpr int which() noexcept
+    {
+        return static_cast<int>(sizeof...(Types)-detail::direct_type<T, Types...>::index - 1);
+    }
+
+    // visitor
+    // unary
+    template <typename F, typename V, typename R = typename detail::result_of_unary_visit<F, first_type>::type>
+    auto VARIANT_INLINE static visit(V const& v, F&& f)
+        -> decltype(detail::dispatcher<F, V, R, Types...>::apply_const(v, std::forward<F>(f)))
+    {
+        return detail::dispatcher<F, V, R, Types...>::apply_const(v, std::forward<F>(f));
+    }
+    // non-const
+    template <typename F, typename V, typename R = typename detail::result_of_unary_visit<F, first_type>::type>
+    auto VARIANT_INLINE static visit(V& v, F&& f)
+        -> decltype(detail::dispatcher<F, V, R, Types...>::apply(v, std::forward<F>(f)))
+    {
+        return detail::dispatcher<F, V, R, Types...>::apply(v, std::forward<F>(f));
+    }
+
+    // binary
+    // const
+    template <typename F, typename V, typename R = typename detail::result_of_binary_visit<F, first_type>::type>
+    auto VARIANT_INLINE static binary_visit(V const& v0, V const& v1, F&& f)
+        -> decltype(detail::binary_dispatcher<F, V, R, Types...>::apply_const(v0, v1, std::forward<F>(f)))
+    {
+        return detail::binary_dispatcher<F, V, R, Types...>::apply_const(v0, v1, std::forward<F>(f));
+    }
+    // non-const
+    template <typename F, typename V, typename R = typename detail::result_of_binary_visit<F, first_type>::type>
+    auto VARIANT_INLINE static binary_visit(V& v0, V& v1, F&& f)
+        -> decltype(detail::binary_dispatcher<F, V, R, Types...>::apply(v0, v1, std::forward<F>(f)))
+    {
+        return detail::binary_dispatcher<F, V, R, Types...>::apply(v0, v1, std::forward<F>(f));
+    }
+
+    // match
+    // unary
+    template <typename... Fs>
+    auto VARIANT_INLINE match(Fs&&... fs) const
+        -> decltype(variant::visit(*this, ::mapbox::util::make_visitor(std::forward<Fs>(fs)...)))
+    {
+        return variant::visit(*this, ::mapbox::util::make_visitor(std::forward<Fs>(fs)...));
+    }
+    // non-const
+    template <typename... Fs>
+    auto VARIANT_INLINE match(Fs&&... fs)
+        -> decltype(variant::visit(*this, ::mapbox::util::make_visitor(std::forward<Fs>(fs)...)))
+    {
+        return variant::visit(*this, ::mapbox::util::make_visitor(std::forward<Fs>(fs)...));
+    }
+
+    ~variant() noexcept // no-throw destructor
+    {
+        helper_type::destroy(type_index, &data);
+    }
+
+    // comparison operators
+    // equality
+    VARIANT_INLINE bool operator==(variant const& rhs) const
+    {
+        assert(valid() && rhs.valid());
+        if (this->which() != rhs.which())
+        {
+            return false;
+        }
+        detail::comparer<variant, detail::equal_comp> visitor(*this);
+        return visit(rhs, visitor);
+    }
+
+    VARIANT_INLINE bool operator!=(variant const& rhs) const
+    {
+        return !(*this == rhs);
+    }
+
+    // less than
+    VARIANT_INLINE bool operator<(variant const& rhs) const
+    {
+        assert(valid() && rhs.valid());
+        if (this->which() != rhs.which())
+        {
+            return this->which() < rhs.which();
+        }
+        detail::comparer<variant, detail::less_comp> visitor(*this);
+        return visit(rhs, visitor);
+    }
+    VARIANT_INLINE bool operator>(variant const& rhs) const
+    {
+        return rhs < *this;
+    }
+    VARIANT_INLINE bool operator<=(variant const& rhs) const
+    {
+        return !(*this > rhs);
+    }
+    VARIANT_INLINE bool operator>=(variant const& rhs) const
+    {
+        return !(*this < rhs);
+    }
+};
+
+// unary visitor interface
+// const
+template <typename F, typename V>
+auto VARIANT_INLINE apply_visitor(F&& f, V const& v) -> decltype(V::visit(v, std::forward<F>(f)))
+{
+    return V::visit(v, std::forward<F>(f));
+}
+
+// non-const
+template <typename F, typename V>
+auto VARIANT_INLINE apply_visitor(F&& f, V& v) -> decltype(V::visit(v, std::forward<F>(f)))
+{
+    return V::visit(v, std::forward<F>(f));
+}
+
+// binary visitor interface
+// const
+template <typename F, typename V>
+auto VARIANT_INLINE apply_visitor(F&& f, V const& v0, V const& v1) -> decltype(V::binary_visit(v0, v1, std::forward<F>(f)))
+{
+    return V::binary_visit(v0, v1, std::forward<F>(f));
+}
+
+// non-const
+template <typename F, typename V>
+auto VARIANT_INLINE apply_visitor(F&& f, V& v0, V& v1) -> decltype(V::binary_visit(v0, v1, std::forward<F>(f)))
+{
+    return V::binary_visit(v0, v1, std::forward<F>(f));
+}
+
+// getter interface
+
+#ifdef HAS_EXCEPTIONS
+template <typename ResultType, typename T>
+auto get(T& var)->decltype(var.template get<ResultType>())
+{
+    return var.template get<ResultType>();
+}
+#endif
+
+template <typename ResultType, typename T>
+ResultType& get_unchecked(T& var)
+{
+    return var.template get_unchecked<ResultType>();
+}
+
+#ifdef HAS_EXCEPTIONS
+template <typename ResultType, typename T>
+auto get(T const& var)->decltype(var.template get<ResultType>())
+{
+    return var.template get<ResultType>();
+}
+#endif
+
+template <typename ResultType, typename T>
+ResultType const& get_unchecked(T const& var)
+{
+    return var.template get_unchecked<ResultType>();
+}
+} // namespace util
+} // namespace mapbox
+
+// hashable iff underlying types are hashable
+namespace std {
+template <typename... Types>
+struct hash< ::mapbox::util::variant<Types...>> {
+    std::size_t operator()(const ::mapbox::util::variant<Types...>& v) const noexcept
+    {
+        return ::mapbox::util::apply_visitor(::mapbox::util::detail::hasher{}, v);
+    }
+};
+}
+
+#endif // MAPBOX_UTIL_VARIANT_HPP
diff --git a/src/include/mapbox/variant_io.hpp b/src/include/mapbox/variant_io.hpp
new file mode 100644
index 0000000..1456cc5
--- /dev/null
+++ b/src/include/mapbox/variant_io.hpp
@@ -0,0 +1,45 @@
+#ifndef MAPBOX_UTIL_VARIANT_IO_HPP
+#define MAPBOX_UTIL_VARIANT_IO_HPP
+
+#include <iosfwd>
+
+#include <mapbox/variant.hpp>
+
+namespace mapbox {
+namespace util {
+
+namespace detail {
+// operator<< helper
+template <typename Out>
+class printer
+{
+public:
+    explicit printer(Out& out)
+        : out_(out) {}
+    printer& operator=(printer const&) = delete;
+
+    // visitor
+    template <typename T>
+    void operator()(T const& operand) const
+    {
+        out_ << operand;
+    }
+
+private:
+    Out& out_;
+};
+}
+
+// operator<<
+template <typename CharT, typename Traits, typename... Types>
+VARIANT_INLINE std::basic_ostream<CharT, Traits>&
+operator<<(std::basic_ostream<CharT, Traits>& out, variant<Types...> const& rhs)
+{
+    detail::printer<std::basic_ostream<CharT, Traits>> visitor(out);
+    apply_visitor(visitor, rhs);
+    return out;
+}
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_VARIANT_IO_HPP
diff --git a/src/include/mapbox/variant_visitor.hpp b/src/include/mapbox/variant_visitor.hpp
new file mode 100644
index 0000000..481eb65
--- /dev/null
+++ b/src/include/mapbox/variant_visitor.hpp
@@ -0,0 +1,38 @@
+#ifndef MAPBOX_UTIL_VARIANT_VISITOR_HPP
+#define MAPBOX_UTIL_VARIANT_VISITOR_HPP
+
+namespace mapbox {
+namespace util {
+
+template <typename... Fns>
+struct visitor;
+
+template <typename Fn>
+struct visitor<Fn> : Fn
+{
+    using type = Fn;
+    using Fn::operator();
+
+    visitor(Fn fn) : Fn(fn) {}
+};
+
+template <typename Fn, typename... Fns>
+struct visitor<Fn, Fns...> : Fn, visitor<Fns...>
+{
+    using type = visitor;
+    using Fn::operator();
+    using visitor<Fns...>::operator();
+
+    visitor(Fn fn, Fns... fns) : Fn(fn), visitor<Fns...>(fns...) {}
+};
+
+template <typename... Fns>
+visitor<Fns...> make_visitor(Fns... fns)
+{
+    return visitor<Fns...>(fns...);
+}
+
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_VARIANT_VISITOR_HPP
diff --git a/src/marked b/src/marked
new file mode 100644
index 0000000..e69de29