diff --git a/trunk/src/comparator.cpp b/trunk/src/comparator.cpp
new file mode 100644
index 0000000..87464b8
--- /dev/null
+++ b/trunk/src/comparator.cpp
@@ -0,0 +1,39 @@
+#include <cstring>
+#include <iostream>
+#include <boost/filesystem/fstream.hpp>
+#include <cassert>
+
+#include "comparator.h"
+
+void comparator::next(const typed_file& filename1, const typed_file& filename2) {
+    if (fs::file_size(filename1.path()) != fs::file_size(filename2.path())) {
+        return;
+    }
+    const int buf_size = 4096;
+    char buf1[buf_size], buf2[buf_size];
+    fs::ifstream file1(filename1.path()), file2(filename2.path());
+    while (true) {
+        file1.read(buf1, buf_size);
+        file2.read(buf2, buf_size);
+        assert(file1.gcount() == file2.gcount());
+        if (file1.gcount() == file2.gcount()) {
+            if (std::memcmp(buf1, buf2, file1.gcount()) != 0) {
+                return;
+            }
+            assert(file1.eof() == file2.eof());
+            if (file1.eof() && file2.eof()) {
+                (*this)(compare_result(filename1.path(), filename2.path()));
+                return;
+            } else
+            if (!file1.eof() && !file2.eof()) {
+                continue;
+            }
+        }
+        return;
+    }
+}
+
+std::ostream& operator<<(std::ostream& o, const compare_result& r) {
+    o << "files " << r.file1() << " and " << r.file2() << " are equal";
+    return o;
+}
diff --git a/trunk/src/comparator.h b/trunk/src/comparator.h
new file mode 100644
index 0000000..5b031b8
--- /dev/null
+++ b/trunk/src/comparator.h
@@ -0,0 +1,23 @@
+#ifndef _COMPARATOR_H_
+#define _COMPARATOR_H_
+
+#include "filesystem.h"
+#include "kleisli.h"
+#include "file_type.h"
+
+class compare_result {
+    const fs::path& _file1;
+    const fs::path& _file2;
+public:
+    compare_result(const fs::path& f1, const fs::path& f2): _file1(f1), _file2(f2) {}
+    const fs::path& file1() const { return _file1; }
+    const fs::path& file2() const { return _file2; }
+};
+
+std::ostream& operator<<(std::ostream& o, const compare_result& r);
+
+struct comparator: category::kleisli::arr< std::pair<typed_file, typed_file>, compare_result> {
+    void next(const typed_file& file1, const typed_file& file2);
+};
+
+#endif
diff --git a/trunk/src/filesystem.cpp b/trunk/src/filesystem.cpp
new file mode 100644
index 0000000..c7818e2
--- /dev/null
+++ b/trunk/src/filesystem.cpp
@@ -0,0 +1,25 @@
+#include <iterator>
+
+#include "filesystem.h"
+#include "logger.h"
+#include "functor_iterator.h"
+
+namespace fs {
+
+void recursive::next(const std::string& value) {
+    if (!exists(value)) {
+        logger::std_stream() << value << " does not exists" << std::endl;
+    } else
+    if (is_directory(value)) {
+        remove_copy_if(recursive_directory_iterator(value), recursive_directory_iterator(),
+            functor_iterator<recursive, fs::path>(*this),
+            std::not1(std::ptr_fun((bool(*)(const path&))(&is_regular_file))));
+    } else
+    if (is_regular_file(value)) {
+        (*this)(value);
+    } else {
+        logger::std_stream() << value << " neither directory nor regular file" << std::endl;
+    }
+}
+
+}