diff --git a/include/asyncpp/core/future.h b/include/asyncpp/core/future.h
index b2f6357..575a5ef 100644
--- a/include/asyncpp/core/future.h
+++ b/include/asyncpp/core/future.h
@@ -6,6 +6,7 @@
 #include "future.pre.h"
 
 #include "future/map.h"
+#include "future/lazy.h"
 #include "future/and_then.h"
 
 namespace asyncpp
diff --git a/include/asyncpp/core/future.inl b/include/asyncpp/core/future.inl
index 6763be1..9834fb1 100644
--- a/include/asyncpp/core/future.inl
+++ b/include/asyncpp/core/future.inl
@@ -3,6 +3,7 @@
 #include "future.h"
 
 #include "future/map.inl"
+#include "future/lazy.inl"
 #include "future/and_then.inl"
 
 #ifdef asyncpp_timing
diff --git a/include/asyncpp/core/future/and_then.h b/include/asyncpp/core/future/and_then.h
index 8cf2ce2..63d441b 100644
--- a/include/asyncpp/core/future/and_then.h
+++ b/include/asyncpp/core/future/and_then.h
@@ -27,10 +27,10 @@ namespace __future {
         using base_future_type          = base_future<value_type, this_type>;
         using result_type               = typename base_future_type::result_type;
 
-    public:
-        lambda_type             lambda;
-        first_future_type       first;
-        second_future_type_ptr  second;
+    private:
+        lambda_type             _lambda;
+        first_future_type       _first;
+        second_future_type_ptr  _second;
 
     public:
         /**
diff --git a/include/asyncpp/core/future/and_then.inl b/include/asyncpp/core/future/and_then.inl
index df34ba7..4e1d737 100644
--- a/include/asyncpp/core/future/and_then.inl
+++ b/include/asyncpp/core/future/and_then.inl
@@ -17,8 +17,8 @@ namespace __future {
         ::and_then_impl(
             X_future&& p_first,
             X_lambda&& p_lambda)
-        : first (std::forward<X_future>(p_first))
-        , lambda(std::forward<X_lambda>(p_lambda))
+        : _first (std::forward<X_future>(p_first))
+        , _lambda(std::forward<X_lambda>(p_lambda))
         { }
 
     template<
@@ -30,17 +30,17 @@ namespace __future {
     {
         while (true)
         {
-            if (second)
+            if (_second)
             {
-                return second->poll();
+                return _second->poll();
             }
             else
             {
-                auto r = first.poll();
+                auto r = _first.poll();
                 if (!r)
                     return result_type::not_ready();
 
-                second = std::make_unique<second_future_type>(r.call(lambda));
+                _second = std::make_unique<second_future_type>(r.call(_lambda));
             }
         }
     }
diff --git a/include/asyncpp/core/future/lazy.h b/include/asyncpp/core/future/lazy.h
new file mode 100644
index 0000000..552021e
--- /dev/null
+++ b/include/asyncpp/core/future/lazy.h
@@ -0,0 +1,64 @@
+#pragma once
+
+#include "../future.pre.h"
+
+namespace asyncpp
+{
+
+    namespace __future
+    {
+
+        template<typename T_lambda>
+        struct lazy_impl final :
+            public base_future<
+                decltype(std::declval<T_lambda>()()),
+                lazy_impl<T_lambda>
+            >
+        {
+        public:
+            using lambda_type       = T_lambda;
+            using value_type        = decltype(std::declval<lambda_type>()());
+            using this_type         = lazy_impl<lambda_type>;
+            using base_future_type  = base_future<value_type, this_type>;
+            using result_type       = typename base_future_type::result_type;
+
+        private:
+            lambda_type _lambda;
+
+        public:
+            /**
+             * @brief Constructor.
+             */
+            template<typename X_lambda>
+            inline lazy_impl(
+                X_lambda&& p_lambda);
+
+        public: /* future */
+            /**
+             * @brief Poll the result from the future.
+             */
+            template<typename X = value_type>
+            inline auto poll()
+                -> std::enable_if_t<
+                    std::is_void_v<X>,
+                    result_type>;
+
+            /**
+             * @brief Poll the result from the future.
+             */
+            template<typename X = value_type>
+            inline auto poll()
+                -> std::enable_if_t<
+                    !std::is_void_v<X>,
+                    result_type>;
+        };
+
+    }
+
+    /**
+     * @brief Create a lazy evaluated future.
+     */
+    template<typename X_lambda>
+    inline auto lazy(X_lambda&& p_lambda);
+
+}
diff --git a/include/asyncpp/core/future/lazy.inl b/include/asyncpp/core/future/lazy.inl
new file mode 100644
index 0000000..60b5f03
--- /dev/null
+++ b/include/asyncpp/core/future/lazy.inl
@@ -0,0 +1,53 @@
+#pragma once
+
+#include "lazy.h"
+
+namespace asyncpp
+{
+
+    namespace __future
+    {
+
+        /* lazy_impl */
+
+        template<typename T_lambda>
+        template<typename X_lambda>
+        lazy_impl<T_lambda>::lazy_impl(
+            X_lambda&& p_lambda)
+            : _lambda(std::forward<X_lambda>(p_lambda))
+            { }
+
+        template<typename T_lambda>
+        template<typename X>
+        inline auto lazy_impl<T_lambda>
+            ::poll()
+                -> std::enable_if_t<
+                    std::is_void_v<X>,
+                    result_type>
+        {
+            _lambda();
+            return result_type::ready();
+        }
+
+        template<typename T_lambda>
+        template<typename X>
+        inline auto lazy_impl<T_lambda>
+            ::poll()
+                -> std::enable_if_t<
+                    !std::is_void_v<X>,
+                    result_type>
+        {
+            return result_type::ready(_lambda());
+        }
+    }
+
+    template<typename X_lambda>
+    inline auto lazy(X_lambda&& p_lambda)
+    {
+        using lambda_type = X_lambda;
+        using lazy_type   = __future::lazy_impl<lambda_type>;
+
+        return lazy_type(std::forward<X_lambda>(p_lambda));
+    }
+
+}
diff --git a/include/asyncpp/core/future/map.h b/include/asyncpp/core/future/map.h
index eed3ede..979c740 100644
--- a/include/asyncpp/core/future/map.h
+++ b/include/asyncpp/core/future/map.h
@@ -23,9 +23,9 @@ namespace __future {
         using base_future_type  = base_future<value_type, this_type>;
         using result_type       = typename base_future_type::result_type;
 
-    public:
-        future_type future;
-        lambda_type lambda;
+    private:
+        future_type _future;
+        lambda_type _lambda;
 
     public:
         /**
diff --git a/include/asyncpp/core/future/map.inl b/include/asyncpp/core/future/map.inl
index bdc6c39..c03d292 100644
--- a/include/asyncpp/core/future/map.inl
+++ b/include/asyncpp/core/future/map.inl
@@ -17,8 +17,8 @@ namespace __future {
         ::map_impl(
             X_future&& p_future,
             X_lambda&& p_lambda)
-        : future(std::forward<X_future>(p_future))
-        , lambda(std::forward<X_lambda>(p_lambda))
+        : _future(std::forward<X_future>(p_future))
+        , _lambda(std::forward<X_lambda>(p_lambda))
         { }
 
     template<
@@ -28,9 +28,9 @@ namespace __future {
     map_impl<T_future, T_lambda>
         ::poll()
     {
-        auto r = future.poll();
+        auto r = _future.poll();
         return r
-            ? result_type::ready(r.call(lambda))
+            ? result_type::ready(r.call(_lambda))
             : result_type::not_ready();
     }
 
diff --git a/include/asyncpp/core/stream.h b/include/asyncpp/core/stream.h
index 46a0d2a..8271f14 100644
--- a/include/asyncpp/core/stream.h
+++ b/include/asyncpp/core/stream.h
@@ -5,8 +5,6 @@
 #include "result.h"
 #include "stream.pre.h"
 
-#include "stream/for_each.h"
-
 namespace asyncpp
 {
 
@@ -47,6 +45,44 @@ namespace asyncpp
         template<typename X_lambda>
         inline auto for_each(X_lambda&& p_lambda) &&;
 
+    public:
+        /**
+         * @brief Transforms the stream from one type to another type
+         *        by executing the passed lambda for each value.
+         */
+        template<typename X_lambda>
+        inline auto map(X_lambda&& p_lambda) const &;
+
+        /**
+         * @brief Transforms the stream from one type to another type
+         *        by executing the passed lambda for each value.
+         */
+        template<typename X_lambda>
+        inline auto map(X_lambda&& p_lambda) &;
+
+        /**
+         * @brief Transforms the stream from one type to another type
+         *        by executing the passed lambda for each value.
+         */
+        template<typename X_lambda>
+        inline auto map(X_lambda&& p_lambda) &&;
+
+    public:
+        /**
+         * @brief Flatten the stream of streams to a single stream.
+         */
+        inline auto flatten() const &;
+
+        /**
+         * @brief Flatten the stream of streams to a single stream.
+         */
+        inline auto flatten() &;
+
+        /**
+         * @brief Flatten the stream of streams to a single stream.
+         */
+        inline auto flatten() &&;
+
     #ifdef asyncpp_timing
     public:
         /**
diff --git a/include/asyncpp/core/stream.inl b/include/asyncpp/core/stream.inl
index bb62afe..9eebd0f 100644
--- a/include/asyncpp/core/stream.inl
+++ b/include/asyncpp/core/stream.inl
@@ -2,6 +2,8 @@
 
 #include "stream.h"
 
+#include "stream/map.inl"
+#include "stream/flatten.inl"
 #include "stream/for_each.inl"
 
 #ifdef asyncpp_timing
@@ -67,6 +69,106 @@ namespace asyncpp
             std::forward<X_lambda>(p_lambda));
     }
 
+    /* base_stream::map */
+
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_stream<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) const &
+    {
+        using lambda_type = X_lambda;
+        using map_type    = __stream::map_impl<derived_type, lambda_type>;
+
+        auto& self = static_cast<derived_type const &>(*this);
+
+        return map_type(
+            std::forward<derived_type const &>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
+
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_stream<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) &
+    {
+        using lambda_type = X_lambda;
+        using map_type    = __stream::map_impl<derived_type, lambda_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return map_type(
+            std::forward<derived_type &>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
+
+    template<
+        typename T_value,
+        typename T_derived>
+    template<
+        typename X_lambda>
+    auto base_stream<T_value, T_derived>
+        ::map(X_lambda&& p_lambda) &&
+    {
+        using lambda_type = X_lambda;
+        using map_type    = __stream::map_impl<derived_type, lambda_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return map_type(
+            std::forward<derived_type &&>(self),
+            std::forward<X_lambda>(p_lambda));
+    }
+
+    /* base_stream::flatten */
+
+    template<
+        typename T_value,
+        typename T_derived>
+    auto base_stream<T_value, T_derived>
+        ::flatten() const &
+    {
+        using flatten_type = __stream::flatten_impl<derived_type>;
+
+        auto& self = static_cast<derived_type const &>(*this);
+
+        return flatten_type(
+            std::forward<derived_type const &>(self));
+    }
+
+    template<
+        typename T_value,
+        typename T_derived>
+    auto base_stream<T_value, T_derived>
+        ::flatten() &
+    {
+        using flatten_type = __stream::flatten_impl<derived_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return flatten_type(
+            std::forward<derived_type &>(self));
+    }
+
+    template<
+        typename T_value,
+        typename T_derived>
+    auto base_stream<T_value, T_derived>
+        ::flatten() &&
+    {
+        using flatten_type = __stream::flatten_impl<derived_type>;
+
+        auto& self = static_cast<derived_type &>(*this);
+
+        return flatten_type(
+            std::forward<derived_type &&>(self));
+    }
+
     /* base_stream::timeout */
 
     #ifdef asyncpp_timing
diff --git a/include/asyncpp/core/stream/flatten.h b/include/asyncpp/core/stream/flatten.h
new file mode 100644
index 0000000..9c61190
--- /dev/null
+++ b/include/asyncpp/core/stream/flatten.h
@@ -0,0 +1,47 @@
+#pragma once
+
+#include <memory>
+
+#include <asyncpp/core/stream.pre.h>
+
+namespace asyncpp {
+namespace __stream {
+
+    template<
+        typename T_stream>
+    struct flatten_impl final :
+        public base_stream<
+            typename T_stream::value_type::value_type,
+            flatten_impl<T_stream>
+        >
+    {
+    public:
+        using stream_type           = T_stream;
+        using inner_stream_type     = typename stream_type::value_type;
+        using inner_stream_ptr_u    = std::unique_ptr<inner_stream_type>;
+        using value_type            = typename inner_stream_type::value_type;
+        using this_type             = flatten_impl<stream_type>;
+        using base_stream_type      = base_stream<value_type, this_type>;
+        using result_type           = typename base_stream_type::result_type;
+
+    private:
+        stream_type         _stream;
+        inner_stream_ptr_u  _inner;
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<
+            typename X_stream>
+        inline flatten_impl(
+            X_stream&& p_stream);
+
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/core/stream/flatten.inl b/include/asyncpp/core/stream/flatten.inl
new file mode 100644
index 0000000..aa1b6d5
--- /dev/null
+++ b/include/asyncpp/core/stream/flatten.inl
@@ -0,0 +1,49 @@
+#pragma once
+
+#include "flatten.h"
+
+namespace asyncpp {
+namespace __stream {
+
+    /* flatten_impl */
+
+    template<
+        typename T_stream>
+    template<
+        typename X_stream>
+    flatten_impl<T_stream>::flatten_impl(
+        X_stream&& p_stream)
+        : _stream   (std::forward<X_stream>(p_stream))
+        , _inner    ()
+        { }
+
+    template<
+        typename T_stream>
+    typename flatten_impl<T_stream>::result_type
+    flatten_impl<T_stream>
+        ::poll()
+    {
+        while (true)
+        {
+            if (_inner)
+            {
+                auto r = _inner->poll();
+
+                if (!r.is_done())
+                    return r;
+
+                _inner.reset();
+            }
+
+            auto r = _stream.poll();
+            if (r.is_done())
+                return result_type::done();
+
+            if (r.is_not_ready())
+                return result_type::not_ready();
+
+            _inner = std::make_unique<inner_stream_type>(std::move(*r));
+        }
+    }
+
+} }
diff --git a/include/asyncpp/core/stream/for_each.h b/include/asyncpp/core/stream/for_each.h
index 491dfed..d31265e 100644
--- a/include/asyncpp/core/stream/for_each.h
+++ b/include/asyncpp/core/stream/for_each.h
@@ -22,9 +22,9 @@ namespace __stream {
         using base_future_type  = base_future<value_type, this_type>;
         using result_type       = typename base_future_type::result_type;
 
-    public:
-        stream_type stream;
-        lambda_type lambda;
+    private:
+        stream_type _stream;
+        lambda_type _lambda;
 
     public:
         /**
diff --git a/include/asyncpp/core/stream/for_each.inl b/include/asyncpp/core/stream/for_each.inl
index 1ad6581..d4e2900 100644
--- a/include/asyncpp/core/stream/for_each.inl
+++ b/include/asyncpp/core/stream/for_each.inl
@@ -17,8 +17,8 @@ namespace __stream {
         ::for_each_impl(
             X_stream&& p_stream,
             X_lambda&& p_lambda)
-        : stream(std::forward<X_stream>(p_stream))
-        , lambda(std::forward<X_lambda>(p_lambda))
+        : _stream(std::forward<X_stream>(p_stream))
+        , _lambda(std::forward<X_lambda>(p_lambda))
         { }
 
     template<
@@ -30,14 +30,14 @@ namespace __stream {
     {
         while (true)
         {
-            auto r = stream.poll();
+            auto r = _stream.poll();
             if (r.is_done())
                 return result_type::ready();
 
             if (r.is_not_ready())
                 return result_type::not_ready();
 
-            r.call(lambda);
+            r.call(_lambda);
         }
     }
 
diff --git a/include/asyncpp/core/stream/map.h b/include/asyncpp/core/stream/map.h
new file mode 100644
index 0000000..d20d1c4
--- /dev/null
+++ b/include/asyncpp/core/stream/map.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include <asyncpp/core/stream.pre.h>
+
+namespace asyncpp {
+namespace __stream {
+
+    template<
+        typename T_stream,
+        typename T_lambda>
+    struct map_impl final :
+        public base_stream<
+            decltype(std::declval<T_lambda>()(std::declval<typename T_stream::value_type>())),
+            map_impl<T_stream, T_lambda>
+        >
+    {
+    public:
+        using stream_type       = T_stream;
+        using lambda_type       = T_lambda;
+        using inner_value_type  = typename stream_type::value_type;
+        using value_type        = decltype(std::declval<lambda_type>()(std::declval<inner_value_type>()));
+        using this_type         = map_impl<stream_type, lambda_type>;
+        using base_stream_type  = base_stream<value_type, this_type>;
+        using result_type       = typename base_stream_type::result_type;
+
+    private:
+        stream_type _stream;
+        lambda_type _lambda;
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<
+            typename X_stream,
+            typename X_lambda>
+        inline map_impl(
+            X_stream&& p_stream,
+            X_lambda&& p_lambda);
+
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/core/stream/map.inl b/include/asyncpp/core/stream/map.inl
new file mode 100644
index 0000000..3235abe
--- /dev/null
+++ b/include/asyncpp/core/stream/map.inl
@@ -0,0 +1,40 @@
+#pragma once
+
+#include "map.h"
+
+namespace asyncpp {
+namespace __stream {
+
+    /* map_impl */
+
+    template<
+        typename T_stream,
+        typename T_lambda>
+    template<
+        typename X_stream,
+        typename X_lambda>
+    map_impl<T_stream, T_lambda>::map_impl(
+        X_stream&& p_stream,
+        X_lambda&& p_lambda)
+        : _stream(std::forward<X_stream>(p_stream))
+        , _lambda(std::forward<X_lambda>(p_lambda))
+        { }
+
+    template<
+        typename T_stream,
+        typename T_lambda>
+    typename map_impl<T_stream, T_lambda>::result_type
+    map_impl<T_stream, T_lambda>
+        ::poll()
+    {
+        auto r = _stream.poll();
+        if (r.is_done())
+            return result_type::done();
+
+        if (r.is_ready())
+            return result_type::ready(r.call(_lambda));
+
+        return result_type::not_ready();
+    }
+
+} }
diff --git a/include/asyncpp/fs.h b/include/asyncpp/fs.h
new file mode 100644
index 0000000..5d95a8e
--- /dev/null
+++ b/include/asyncpp/fs.h
@@ -0,0 +1,5 @@
+#pragma once
+
+#include "fs/directory.h"
+
+#include "fs/directory.inl"
diff --git a/include/asyncpp/fs/directory.h b/include/asyncpp/fs/directory.h
new file mode 100644
index 0000000..88e6c0c
--- /dev/null
+++ b/include/asyncpp/fs/directory.h
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <string>
+
+#include <cppfs/path.h>
+
+#include <asyncpp/core/stream.pre.h>
+#include <asyncpp/core/future/lazy.h>
+
+namespace asyncpp {
+namespace fs {
+
+    /**
+     * @brief Create future to read the content of a directory.
+     */
+    inline auto read_dir(const cppfs::path& p_path);
+
+    /**
+     * @brief Create future to read the content of a directory including the subdirectories.
+     */
+    inline auto read_dir_all(const cppfs::path& p_path);
+
+    /**
+     * @brief Create a new future to create a directory.
+     */
+    inline auto create_dir(const cppfs::path& p_path);
+
+    /**
+     * @brief Create a new future to create a directory and all it's parent directories.
+     */
+    inline auto create_dir_all(const cppfs::path& p_path);
+
+    /**
+     * @brief Create a new future to remove an empty directory.
+     */
+    inline auto remove_dir(const cppfs::path& p_path);
+
+    /**
+     * @brief Create a new future to remove a directory and all it's content.
+     */
+    inline auto remove_dir_all(const cppfs::path& p_path);
+
+} }
diff --git a/include/asyncpp/fs/directory.inl b/include/asyncpp/fs/directory.inl
new file mode 100644
index 0000000..975f4e3
--- /dev/null
+++ b/include/asyncpp/fs/directory.inl
@@ -0,0 +1,167 @@
+#pragma once
+
+#include <vector>
+
+#include <cppfs/directory.h>
+
+#include "directory.h"
+
+namespace asyncpp {
+namespace fs {
+
+    namespace __impl
+    {
+
+        struct read_dir_impl
+            : public base_stream<
+                cppfs::directory::entry,
+                read_dir_impl>
+        {
+        public:
+            using value_type        = cppfs::directory::entry;
+            using this_type         = read_dir_impl;
+            using base_future_type  = base_stream<value_type, this_type>;
+            using result_type       = typename base_future_type::result_type;
+
+        private:
+            cppfs::directory::iterator  _it;
+            cppfs::directory::iterator  _end;
+
+        public:
+            inline read_dir_impl(
+                const cppfs::path& p_path)
+            {
+                cppfs::directory d(p_path);
+                if (d.exists())
+                {
+                    _it  = d.begin();
+                    _end = d.end();
+                }
+            }
+
+        public:
+            inline result_type poll()
+            {
+                if (_it == _end)
+                    return result_type::done();
+
+                auto ret = result_type::ready(*_it);
+                ++_it;
+                return ret;
+            }
+        };
+
+        struct read_dir_all_impl
+            : public base_stream<
+                cppfs::directory::entry,
+                read_dir_all_impl>
+        {
+        public:
+            using value_type        = cppfs::directory::entry;
+            using this_type         = read_dir_impl;
+            using base_future_type  = base_stream<value_type, this_type>;
+            using result_type       = typename base_future_type::result_type;
+
+        private:
+            struct entry
+            {
+                cppfs::directory::iterator  it;
+                cppfs::directory::iterator  end;
+            };
+
+            using entry_stack = std::vector<entry>;
+
+            entry_stack _stack;
+
+        public:
+            inline read_dir_all_impl(
+                const cppfs::path& p_path)
+            {
+                cppfs::directory d(p_path);
+                if (d.exists())
+                {
+                    _stack.emplace_back(entry {
+                        d.begin(),
+                        d.end()
+                    });
+                }
+            }
+
+        public:
+            inline result_type poll()
+            {
+                while (true)
+                {
+                    if (_stack.empty())
+                        return result_type::done();
+
+                    auto& e = _stack.back();
+                    if (e.it == e.end)
+                    {
+                        _stack.pop_back();
+                        continue;
+                    }
+
+                    auto ret = result_type::ready(std::move(*e.it));
+                    cppfs::directory d(e.it->path);
+
+                    ++e.it;
+
+                    if (d.exists())
+                    {
+                        _stack.emplace_back(entry {
+                            d.begin(),
+                            d.end(),
+                        });
+                    }
+
+                    return ret;
+                }
+            }
+        };
+
+    }
+
+    auto read_dir(const cppfs::path& p_path)
+    {
+        return __impl::read_dir_impl(p_path);
+    }
+
+    auto read_dir_all(const cppfs::path& p_path)
+    {
+        return __impl::read_dir_all_impl(p_path);
+    }
+
+    auto create_dir(const cppfs::path& p_path)
+    {
+        return lazy([d = cppfs::directory(p_path)]{
+            if (!d.exists())
+                d.create(false);
+        });
+    }
+
+    auto create_dir_all(const cppfs::path& p_path)
+    {
+        return lazy([d = cppfs::directory(p_path)]{
+            if (!d.exists())
+                d.create(true);
+        });
+    }
+
+    auto remove_dir(const cppfs::path& p_path)
+    {
+        return lazy([d = cppfs::directory(p_path)]{
+            if (d.exists())
+                d.remove(false);
+        });
+    }
+
+    auto remove_dir_all(const cppfs::path& p_path)
+    {
+        return lazy([d = cppfs::directory(p_path)]{
+            if (d.exists())
+                d.remove(true);
+        });
+    }
+
+} }
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index afd6aa9..975a22a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -4,6 +4,7 @@ Include                             ( cotire        OPTIONAL RESULT_VARIABLE HAS
 Include                             ( pedantic      OPTIONAL RESULT_VARIABLE HAS_PEDANTIC )
 Include                             ( strip_symbols OPTIONAL RESULT_VARIABLE HAS_STRIP_SYMBOLS )
 
+Find_Package                        ( cppfs REQUIRED )
 Find_Package                        ( cppcore REQUIRED )
 
 # Interface Library ###############################################################################
@@ -16,6 +17,7 @@ Target_Include_Directories          ( asyncpp
                                         $<INSTALL_INTERFACE:${ASYNCPP_INSTALL_DIR_INCLUDE}> )
 Target_Link_Libraries               ( asyncpp
                                       INTERFACE
+                                        cppfs::cppfs
                                         cppcore::cppcore )
 
 # Install #########################################################################################
diff --git a/test/asyncpp/core/future_tests.cpp b/test/asyncpp/core/future_tests.cpp
index 3901406..6a578c1 100644
--- a/test/asyncpp/core/future_tests.cpp
+++ b/test/asyncpp/core/future_tests.cpp
@@ -72,5 +72,21 @@ TEST(future_tests, and_then)
     auto r = f.poll();
     ASSERT_TRUE(r);
     ASSERT_EQ  (5, *r);
-    ASSERT_EQ  (2, f.first._count);
+}
+
+TEST(future_tests, lazy)
+{
+    int i = 1;
+    auto f = lazy([&]{
+        ++i;
+        return i + 1;
+    });
+
+    ASSERT_EQ(i, 1);
+
+    auto r = f.poll();
+
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (2, i);
+    ASSERT_EQ  (3, *r);
 }
diff --git a/test/asyncpp/core/stream_tests.cpp b/test/asyncpp/core/stream_tests.cpp
index e489ca0..b9e2213 100644
--- a/test/asyncpp/core/stream_tests.cpp
+++ b/test/asyncpp/core/stream_tests.cpp
@@ -73,3 +73,72 @@ TEST(stream_tests, for_each)
     auto r = f.poll();
     ASSERT_TRUE(r);
 }
+
+TEST(stream_tests, map)
+{
+    delay d { 5, 0, 0 };
+    auto s = d
+        .map([](int i){
+            return std::to_string(i);
+        });
+
+    auto r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, "1");
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, "2");
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, "3");
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, "4");
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, "5");
+
+    r = s.poll();
+    ASSERT_TRUE(r.is_done());
+}
+
+TEST(stream_tests, flatten)
+{
+    delay d { 3, 0, 0 };
+    auto s = d
+        .map([](int i){
+            return delay { i * 100 + 2, 0, i * 100 };
+        })
+        .flatten();
+
+    auto r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 101);
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 102);
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 201);
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 202);
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 301);
+
+    r = s.poll();
+    ASSERT_TRUE(r);
+    ASSERT_EQ  (*r, 302);
+
+    r = s.poll();
+    ASSERT_TRUE(r.is_done());
+}
diff --git a/test/asyncpp/fs/directory_tests.cpp b/test/asyncpp/fs/directory_tests.cpp
new file mode 100644
index 0000000..679bfe4
--- /dev/null
+++ b/test/asyncpp/fs/directory_tests.cpp
@@ -0,0 +1,210 @@
+#include <gtest/gtest.h>
+
+#include <asyncpp.h>
+#include <asyncpp/fs.h>
+
+using namespace ::testing;
+using namespace ::asyncpp;
+
+struct auto_remove_dir
+    : public cppfs::directory
+{
+public:
+    using cppfs::directory::directory;
+
+    inline ~auto_remove_dir()
+    {
+        if (exists())
+            remove(true);
+    }
+};
+
+class directory_tests
+    : public ::testing::Test
+{
+protected:
+    static const std::string& path_test_dir()
+    {
+        static const std::string value("/tmp/asyncpp/test");
+        return value;
+    }
+
+    static const std::string& path_test_dir_single()
+    {
+        static const std::string value("/tmp/asyncpp/test/single");
+        return value;
+    }
+
+    static const std::string& path_test_dir_parent()
+    {
+        static const std::string value("/tmp/asyncpp/test/parent");
+        return value;
+    }
+
+    static const std::string& path_test_dir_child()
+    {
+        static const std::string value("/tmp/asyncpp/test/parent/child");
+        return value;
+    }
+
+    void SetUp() override
+    {
+        cppfs::directory d(path_test_dir());
+        if (!d.exists())
+            d.create(true);
+    }
+
+    void TearDown() override
+    {
+        cppfs::directory d(path_test_dir());
+        if (d.exists())
+            d.remove(true);
+    }
+};
+
+TEST_F(directory_tests, read_dir)
+{
+    using namespace cppfs;
+    using namespace std::string_literals;
+
+    auto s = fs::read_dir("."s);
+    auto v = std::vector<std::string>();
+    auto r = decltype(s)::result_type::not_ready();
+
+    while ((r = s.poll()).is_ready())
+        v.emplace_back(r->path.parts().back());
+
+    ASSERT_TRUE(r.is_done());
+
+    std::sort(v.begin(), v.end(), cppcore::op_invariant_string_less { });
+    EXPECT_EQ(v, std::vector<std::string>({
+        "asyncpp",
+        "CMakeLists.txt",
+        "helper",
+    }));
+}
+
+TEST_F(directory_tests, read_dir_all)
+{
+    using namespace cppfs;
+    using namespace std::string_literals;
+
+    auto s = fs::read_dir_all("."s);
+    auto r = decltype(s)::result_type::not_ready();
+
+    auto entries = std::vector<cppfs::directory::entry>();
+    while ((r = s.poll()).is_ready())
+        entries.emplace_back(*r);
+
+    ASSERT_TRUE(r.is_done());
+
+    std::sort(entries.begin(), entries.end());
+
+    std::vector<std::string> paths;
+    paths.reserve(entries.size());
+    std::transform(
+        entries.begin(),
+        entries.end(),
+        std::back_inserter(paths),
+        [](auto& e) {
+            auto s = std::to_string(static_cast<int>(e.type)) + e.path.str();
+            return s;
+        });
+
+    EXPECT_EQ(paths, std::vector<std::string>({
+        "1./asyncpp",
+        "1./asyncpp/core",
+        "2./asyncpp/core/future_tests.cpp",
+        "2./asyncpp/core/result_tests.cpp",
+        "2./asyncpp/core/stream_tests.cpp",
+        "2./asyncpp/core/task_tests.cpp",
+        "1./asyncpp/executor",
+        "2./asyncpp/executor/current_thread_tests.cpp",
+        "1./asyncpp/fs",
+        "2./asyncpp/fs/directory_tests.cpp",
+        "1./asyncpp/timing",
+        "2./asyncpp/timing/delay_tests.cpp",
+        "2./asyncpp/timing/interval_tests.cpp",
+        "2./asyncpp/timing/timeout_tests.cpp",
+        "2./asyncpp/timing/timer_tests.cpp",
+        "1./helper",
+        "2./helper/now_mock.h",
+        "2./helper/runtime_mock.h",
+        "2./helper/test_delay.h",
+        "2./CMakeLists.txt",
+    }));
+}
+
+TEST_F(directory_tests, create_dir)
+{
+    auto f =
+        lazy([path=path_test_dir_single()]{
+            return path;
+        })
+        .and_then(fs::create_dir);
+
+    auto_remove_dir d(path_test_dir_single());
+
+    ASSERT_FALSE(d.exists());
+
+    auto r = f.poll();
+
+    ASSERT_TRUE (r);
+    ASSERT_TRUE (d.exists());
+}
+
+TEST_F(directory_tests, create_dir_all)
+{
+    auto f =
+        lazy([path=path_test_dir_child()]{
+            return path;
+        })
+        .and_then(fs::create_dir_all);
+
+    auto_remove_dir d(path_test_dir_child());
+
+    ASSERT_FALSE(d.exists());
+
+    auto r = f.poll();
+
+    ASSERT_TRUE (r);
+    ASSERT_TRUE (d.exists());
+}
+
+TEST_F(directory_tests, remove_dir)
+{
+    auto f =
+        lazy([path=path_test_dir_single()]{
+            return path;
+        })
+        .and_then(fs::remove_dir);
+
+    auto_remove_dir d(path_test_dir_single());
+    d.create(true);
+
+    ASSERT_TRUE (d.exists());
+
+    auto r = f.poll();
+
+    ASSERT_TRUE (r);
+    ASSERT_FALSE(d.exists());
+}
+
+TEST_F(directory_tests, remove_dir_all)
+{
+    auto f =
+        lazy([path=path_test_dir_parent()]{
+            return path;
+        })
+        .and_then(fs::remove_dir_all);
+
+    auto_remove_dir d(path_test_dir_child());
+    d.create(true);
+
+    ASSERT_TRUE (d.exists());
+
+    auto r = f.poll();
+
+    ASSERT_TRUE (r);
+    ASSERT_FALSE(d.exists());
+}