diff --git a/.ignore b/.ignore
index 6912fef..32801c9 100644
--- a/.ignore
+++ b/.ignore
@@ -1 +1 @@
-deps/
+deps/tree-sitter-lang
diff --git a/deps/termcolor/.gitignore b/deps/termcolor/.gitignore
new file mode 100644
index 0000000..f0b7474
--- /dev/null
+++ b/deps/termcolor/.gitignore
@@ -0,0 +1,2 @@
+.xmake
+compile_commands.json
diff --git a/deps/termcolor/LICENSE b/deps/termcolor/LICENSE
new file mode 100644
index 0000000..e2a9f53
--- /dev/null
+++ b/deps/termcolor/LICENSE
@@ -0,0 +1,31 @@
+Copyright (c) 2013, Ihor Kalnytskyi.
+All rights reserved.
+
+Redistribution and use in source and binary forms of the software as well
+as documentation, with or without modification, are permitted provided
+that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the following
+  disclaimer in the documentation and/or other materials provided
+  with the distribution.
+
+* The names of the contributors may not be used to endorse or
+  promote products derived from this software without specific
+  prior written permission.
+
+THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
+NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE AND DOCUMENTATION, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
diff --git a/deps/termcolor/termcolor.hpp b/deps/termcolor/termcolor.hpp
new file mode 100644
index 0000000..d94e991
--- /dev/null
+++ b/deps/termcolor/termcolor.hpp
@@ -0,0 +1,939 @@
+//!
+//! termcolor
+//! ~~~~~~~~~
+//!
+//! termcolor is a header-only c++ library for printing colored messages
+//! to the terminal. Written just for fun with a help of the Force.
+//!
+//! :copyright: (c) 2013 by Ihor Kalnytskyi
+//! :license: BSD, see LICENSE for details
+//!
+
+#ifndef TERMCOLOR_HPP_
+#define TERMCOLOR_HPP_
+
+#include <iostream>
+
+// Detect target's platform and set some macros in order to wrap platform
+// specific code this library depends on.
+#if defined(_WIN32) || defined(_WIN64)
+#   define TERMCOLOR_TARGET_WINDOWS
+#elif defined(__unix__) || defined(__unix) || (defined(__APPLE__) && defined(__MACH__))
+#   define TERMCOLOR_TARGET_POSIX
+#endif
+
+// If implementation has not been explicitly set, try to choose one based on
+// target platform.
+#if !defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES) && !defined(TERMCOLOR_USE_WINDOWS_API) && !defined(TERMCOLOR_USE_NOOP)
+#   if defined(TERMCOLOR_TARGET_POSIX)
+#       define TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES
+#       define TERMCOLOR_AUTODETECTED_IMPLEMENTATION
+#   elif defined(TERMCOLOR_TARGET_WINDOWS)
+#       define TERMCOLOR_USE_WINDOWS_API
+#       define TERMCOLOR_AUTODETECTED_IMPLEMENTATION
+#   endif
+#endif
+
+// These headers provide isatty()/fileno() functions, which are used for
+// testing whether a standard stream refers to the terminal.
+#if defined(TERMCOLOR_TARGET_POSIX)
+#   include <unistd.h>
+#elif defined(TERMCOLOR_TARGET_WINDOWS)
+#   include <io.h>
+#   include <windows.h>
+#endif
+
+
+namespace termcolor
+{
+    // Forward declaration of the `_internal` namespace.
+    // All comments are below.
+    namespace _internal
+    {
+        inline int colorize_index();
+        inline FILE* get_standard_stream(const std::ostream& stream);
+        inline FILE* get_standard_stream(const std::wostream& stream);
+        template <typename CharT>
+        bool is_colorized(std::basic_ostream<CharT>& stream);
+        template <typename CharT>
+        bool is_atty(const std::basic_ostream<CharT>& stream);
+
+    #if defined(TERMCOLOR_TARGET_WINDOWS)
+        template <typename CharT>
+        void win_change_attributes(std::basic_ostream<CharT>& stream, int foreground, int background = -1);
+    #endif
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& colorize(std::basic_ostream<CharT>& stream)
+    {
+        stream.iword(_internal::colorize_index()) = 1L;
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& nocolorize(std::basic_ostream<CharT>& stream)
+    {
+        stream.iword(_internal::colorize_index()) = 0L;
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& reset(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[00m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1, -1);
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bold(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[1m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& dark(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[2m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& italic(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[3m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& underline(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[4m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1, COMMON_LVB_UNDERSCORE);
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& blink(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[5m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& reverse(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[7m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& concealed(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[8m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& crossed(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[9m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+    
+    template <uint8_t code, typename CharT>
+    std::basic_ostream<CharT>& color(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[38;5;" << +code << "m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <uint8_t code, typename CharT>
+    std::basic_ostream<CharT>& on_color(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[48;5;" << +code << "m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <uint8_t r, uint8_t g, uint8_t b, typename CharT>
+    std::basic_ostream<CharT>& color(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[38;2;" << +r << ";" << +g << ";" << +b << "m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <uint8_t r, uint8_t g, uint8_t b, typename CharT>
+    std::basic_ostream<CharT>& on_color(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[48;2;" << +r << ";" << +g << ";" << +b << "m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& grey(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[30m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                0   // grey (black)
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& red(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[31m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& green(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[32m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_GREEN
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& yellow(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[33m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_GREEN | FOREGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& blue(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[34m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& magenta(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[35m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& cyan(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[36m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_GREEN
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& white(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[37m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_GREEN | FOREGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_grey(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[90m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                0 | FOREGROUND_INTENSITY   // grey (black)
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_red(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[91m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_RED | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_green(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[92m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_GREEN | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_yellow(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[93m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_GREEN | FOREGROUND_RED | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_blue(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[94m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_magenta(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[95m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_RED | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_cyan(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[96m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_GREEN | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& bright_white(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[97m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream,
+                FOREGROUND_BLUE | FOREGROUND_GREEN | FOREGROUND_RED | FOREGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_grey(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[40m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                0   // grey (black)
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_red(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[41m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_green(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[42m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_yellow(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[43m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_blue(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[44m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_BLUE
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_magenta(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[45m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_BLUE | BACKGROUND_RED
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_cyan(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[46m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_BLUE
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_white(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[47m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_BLUE | BACKGROUND_RED
+            );
+        #endif
+        }
+
+        return stream;
+    }
+
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_grey(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[100m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                0 | BACKGROUND_INTENSITY   // grey (black)
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_red(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[101m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_RED | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_green(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[102m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_yellow(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[103m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_RED | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_blue(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[104m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_BLUE | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_magenta(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[105m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_BLUE | BACKGROUND_RED | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_cyan(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[106m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_BLUE | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+        return stream;
+    }
+
+    template <typename CharT>
+    std::basic_ostream<CharT>& on_bright_white(std::basic_ostream<CharT>& stream)
+    {
+        if (_internal::is_colorized(stream))
+        {
+        #if defined(TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES)
+            stream << "\033[107m";
+        #elif defined(TERMCOLOR_USE_WINDOWS_API)
+            _internal::win_change_attributes(stream, -1,
+                BACKGROUND_GREEN | BACKGROUND_BLUE | BACKGROUND_RED | BACKGROUND_INTENSITY
+            );
+        #endif
+        }
+
+        return stream;
+    }
+
+
+
+    //! Since C++ hasn't a way to hide something in the header from
+    //! the outer access, I have to introduce this namespace which
+    //! is used for internal purpose and should't be access from
+    //! the user code.
+    namespace _internal
+    {
+        // An index to be used to access a private storage of I/O streams. See
+        // colorize / nocolorize I/O manipulators for details. Due to the fact
+        // that static variables ain't shared between translation units, inline
+        // function with local static variable is used to do the trick and share
+        // the variable value between translation units.
+        inline int colorize_index()
+        {
+            static int colorize_index = std::ios_base::xalloc();
+            return colorize_index;
+        }
+
+        //! Since C++ hasn't a true way to extract stream handler
+        //! from the a given `std::ostream` object, I have to write
+        //! this kind of hack.
+        inline
+        FILE* get_standard_stream(const std::ostream& stream)
+        {
+            if (&stream == &std::cout)
+                return stdout;
+            else if (&stream == &std::cerr || &stream == &std::clog)
+                return stderr;
+
+            return nullptr;
+        }
+
+        //! Since C++ hasn't a true way to extract stream handler
+        //! from the a given `std::wostream` object, I have to write
+        //! this kind of hack.
+        inline
+        FILE* get_standard_stream(const std::wostream& stream)
+        {
+            if (&stream == &std::wcout)
+                return stdout;
+            else if (&stream == &std::wcerr || &stream == &std::wclog)
+                return stderr;
+
+            return nullptr;
+        }
+
+        // Say whether a given stream should be colorized or not. It's always
+        // true for ATTY streams and may be true for streams marked with
+        // colorize flag.
+        template <typename CharT>
+        bool is_colorized(std::basic_ostream<CharT>& stream)
+        {
+            return is_atty(stream) || static_cast<bool>(stream.iword(colorize_index()));
+        }
+
+        //! Test whether a given `std::ostream` object refers to
+        //! a terminal.
+        template <typename CharT>
+        bool is_atty(const std::basic_ostream<CharT>& stream)
+        {
+            FILE* std_stream = get_standard_stream(stream);
+
+            // Unfortunately, fileno() ends with segmentation fault
+            // if invalid file descriptor is passed. So we need to
+            // handle this case gracefully and assume it's not a tty
+            // if standard stream is not detected, and 0 is returned.
+            if (!std_stream)
+                return false;
+
+        #if defined(TERMCOLOR_TARGET_POSIX)
+            return ::isatty(fileno(std_stream));
+        #elif defined(TERMCOLOR_TARGET_WINDOWS)
+            return ::_isatty(_fileno(std_stream));
+        #else
+            return false;
+        #endif
+        }
+
+    #if defined(TERMCOLOR_TARGET_WINDOWS)
+    
+        //! same hack as used in get_standard_stream function, but for Windows with `std::ostream`
+        inline HANDLE get_terminal_handle(std::ostream& stream)
+        {
+            if (&stream == &std::cout)
+                return GetStdHandle(STD_OUTPUT_HANDLE);
+            else if (&stream == &std::cerr || &stream == &std::clog)
+                return GetStdHandle(STD_ERROR_HANDLE);
+            return nullptr;
+        }
+        
+        //! same hack as used in get_standard_stream function, but for Windows with `std::wostream`
+        inline HANDLE get_terminal_handle(std::wostream& stream)
+        {
+            if (&stream == &std::wcout)
+                return GetStdHandle(STD_OUTPUT_HANDLE);
+            else if (&stream == &std::wcerr || &stream == &std::wclog)
+                return GetStdHandle(STD_ERROR_HANDLE);
+            return nullptr;
+        }
+        
+        //! Change Windows Terminal colors attribute. If some
+        //! parameter is `-1` then attribute won't changed.
+        template <typename CharT>
+        void win_change_attributes(std::basic_ostream<CharT>& stream, int foreground, int background)
+        {
+            // yeah, i know.. it's ugly, it's windows.
+            static WORD defaultAttributes = 0;
+
+            // Windows doesn't have ANSI escape sequences and so we use special
+            // API to change Terminal output color. That means we can't
+            // manipulate colors by means of "std::stringstream" and hence
+            // should do nothing in this case.
+            if (!_internal::is_atty(stream))
+                return;
+
+            // get terminal handle
+            HANDLE hTerminal = INVALID_HANDLE_VALUE;
+            hTerminal = get_terminal_handle(stream);
+
+            // save default terminal attributes if it unsaved
+            if (!defaultAttributes)
+            {
+                CONSOLE_SCREEN_BUFFER_INFO info;
+                if (!GetConsoleScreenBufferInfo(hTerminal, &info))
+                    return;
+                defaultAttributes = info.wAttributes;
+            }
+
+            // restore all default settings
+            if (foreground == -1 && background == -1)
+            {
+                SetConsoleTextAttribute(hTerminal, defaultAttributes);
+                return;
+            }
+
+            // get current settings
+            CONSOLE_SCREEN_BUFFER_INFO info;
+            if (!GetConsoleScreenBufferInfo(hTerminal, &info))
+                return;
+
+            if (foreground != -1)
+            {
+                info.wAttributes &= ~(info.wAttributes & 0x0F);
+                info.wAttributes |= static_cast<WORD>(foreground);
+            }
+
+            if (background != -1)
+            {
+                info.wAttributes &= ~(info.wAttributes & 0xF0);
+                info.wAttributes |= static_cast<WORD>(background);
+            }
+
+            SetConsoleTextAttribute(hTerminal, info.wAttributes);
+        }
+    #endif // TERMCOLOR_TARGET_WINDOWS
+
+    } // namespace _internal
+
+} // namespace termcolor
+
+
+#undef TERMCOLOR_TARGET_POSIX
+#undef TERMCOLOR_TARGET_WINDOWS
+
+#if defined(TERMCOLOR_AUTODETECTED_IMPLEMENTATION)
+#   undef TERMCOLOR_USE_ANSI_ESCAPE_SEQUENCES
+#   undef TERMCOLOR_USE_WINDOWS_API
+#endif
+
+#endif // TERMCOLOR_HPP_
diff --git a/deps/termcolor/xmake.lua b/deps/termcolor/xmake.lua
new file mode 100644
index 0000000..7e8083e
--- /dev/null
+++ b/deps/termcolor/xmake.lua
@@ -0,0 +1,7 @@
+set_languages("c++20")
+
+target("termcolor")
+    set_kind("headeronly")
+    add_headerfiles("termcolor.hpp")
+    set_warnings("all", "error")
+    set_rundir("$(projectdir)")
diff --git a/lang/app/main.cpp b/lang/app/main.cpp
index 30355ef..9bfc041 100644
--- a/lang/app/main.cpp
+++ b/lang/app/main.cpp
@@ -11,8 +11,8 @@ int main(int argc, char **argv) {
 
   //
 
-  SourcesManager sources_manager;
+  SourcesManager sources_manager(Log({}, {}));
 
-  sources_manager.add_file(filename);
-  sources_manager.print(std::cout);
+  sources_manager.AddFile(filename);
+  sources_manager.Print(std::cout);
 }
diff --git a/lang/app/sources_manager.hpp b/lang/app/sources_manager.hpp
index 77cdc1a..4e3db4a 100644
--- a/lang/app/sources_manager.hpp
+++ b/lang/app/sources_manager.hpp
@@ -2,8 +2,8 @@
 
 #include "basic_printers.hpp"
 #include "error_handling.hpp"
-#include "error_log.hpp"
 #include "expression_nodes.hpp"
+#include "log.hpp"
 #include "name_tree.hpp"
 #include "statement_builders.hpp"
 #include "statement_nodes.hpp"
@@ -17,7 +17,11 @@
 
 class SourcesManager {
 public:
-  void add_file(const std::string &filename) {
+  SourcesManager(Log &&log) : log_(std::move(log)) {}
+
+  void AddFile(const std::string &filename) {
+    Log::Context logc(log_, utils::Log::Area::kParse);
+
     std::ifstream in;
     in.open(filename);
 
@@ -32,8 +36,8 @@ public:
     parser::ParseTree parse_tree(source);
 
     if (!parse_tree.is_properly_parsed()) {
-      error_handling::handle_parsing_error(
-          "There are some parsing errors in file", parse_tree.get_root());
+      logc.Fatal<Log::kProc>(
+          {{"There are some parsing errors in file"}} /*,parse_tree.get_root()*/);
     }
 
     auto new_statements = builders::build_source_file(
@@ -47,36 +51,36 @@ public:
     new_statements.clear();
   }
 
-  void print(std::ostream &out) {
+  void Print(std::ostream &out) {
     printers::Printer printer(out, 2, 80, true);
     printers::print(statements_, printer);
   }
 
   //
 
-  nodes::ExpressionStorage *expressions() { return &expression_storage_; }
+  nodes::ExpressionStorage &expressions() { return expression_storage_; }
 
-  const nodes::ExpressionStorage *expressions() const {
-    return &expression_storage_;
+  const nodes::ExpressionStorage &expressions() const {
+    return expression_storage_;
   }
 
   //
 
-  nodes::TypeStorage *types() { return &type_storage_; }
+  nodes::TypeStorage &types() { return type_storage_; }
 
-  const nodes::TypeStorage *types() const { return &type_storage_; }
+  const nodes::TypeStorage &types() const { return type_storage_; }
 
   //
 
-  names::NameTree *names() { return &name_tree_; }
+  names::NameTree &names() { return name_tree_; }
 
-  const names::NameTree *names() const { return &name_tree_; }
+  const names::NameTree &names() const { return name_tree_; }
 
   //
 
-  error_handling::ErrorLog *errors() { return &error_log_; }
+  utils::Log &log() { return log_; }
 
-  const error_handling::ErrorLog *errors() const { return &error_log_; }
+  const utils::Log &log() const { return log_; }
 
   //
 
@@ -89,9 +93,9 @@ public:
   }
 
 private:
-  nodes::ExpressionStorage expression_storage_;
-  nodes::TypeStorage type_storage_;
-  names::NameTree name_tree_;
-  error_handling::ErrorLog error_log_;
-  std::vector<nodes::Statement> statements_;
+  Log log_;
+  nodes::ExpressionStorage expression_storage_ = {};
+  nodes::TypeStorage type_storage_ = {};
+  names::NameTree name_tree_ = {};
+  std::vector<nodes::Statement> statements_ = {};
 };
diff --git a/lang/type_check/src/expression_type_check.cpp b/lang/type_check/src/expression_type_check.cpp
index fea52a4..aab879f 100644
--- a/lang/type_check/src/expression_type_check.cpp
+++ b/lang/type_check/src/expression_type_check.cpp
@@ -2,7 +2,6 @@
 #include "basic_nodes.hpp"
 #include "basic_type_check.hpp"
 #include "builtin_types.hpp"
-#include "error_log.hpp"
 #include "sources_manager.hpp"
 #include "type_nodes.hpp"
 #include "utils.hpp"
diff --git a/lang/utils/include/error_log.hpp b/lang/utils/include/error_log.hpp
index 129c237..2ac0c4e 100644
--- a/lang/utils/include/error_log.hpp
+++ b/lang/utils/include/error_log.hpp
@@ -3,6 +3,7 @@
 #include "basic_nodes.hpp"
 #include "basic_printers.hpp"
 
+#include <string>
 #include <vector>
 
 namespace error_handling {
diff --git a/lang/utils/include/executor.hpp b/lang/utils/include/executor.hpp
new file mode 100644
index 0000000..d9fbc5c
--- /dev/null
+++ b/lang/utils/include/executor.hpp
@@ -0,0 +1,79 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+
+#include "log.hpp"
+
+namespace utils {
+
+template <typename... States> class Task;
+
+template <typename State> class ExecutorState {
+public:
+  struct Tag {};
+
+  ExecutorState(State &&state) : state_(std::move(state)) {}
+
+  //
+
+  State &state(Tag) { return state; }
+  const State &state(Tag) const { return state; }
+
+protected:
+  State state_;
+};
+
+template <typename... States> class Executor : public ExecutorState<States>... {
+  friend class Task<States...>;
+
+public:
+  Executor(Log &&log, States &&...states)
+      : ExecutorState<States>(std::move(states))..., log_(std::move(log)) {}
+
+  //
+
+  template <typename T, typename... Args> T New(Args... args) {
+    return T(*this, args...);
+  }
+
+  //
+
+  Log &log() { return log_; }
+  const Log &log() const { return log_; }
+
+private:
+  Log log_;
+};
+
+template <typename... States> class Task {
+public:
+  Task(Executor<States...> &executor) : executor(executor) {}
+
+  virtual ~Task() {}
+
+  //
+
+  virtual void operator()() = 0;
+
+  template <typename T, typename... Args> T New(Args... args) {
+    return executor.template New<T>(std::move(args)...);
+  }
+
+  //
+
+  template <typename T> T &state() {
+    return executor.state(ExecutorState<T>::Tag);
+  }
+  template <typename T> const T &state() const {
+    return executor.state(ExecutorState<T>::Tag);
+  }
+
+  Log &log() { return executor.log_; }
+  const Log &log() const { return executor.log_; }
+
+public:
+  Executor<States...> &executor;
+};
+
+} // namespace utils
diff --git a/lang/utils/include/log.hpp b/lang/utils/include/log.hpp
new file mode 100644
index 0000000..8e3ef2d
--- /dev/null
+++ b/lang/utils/include/log.hpp
@@ -0,0 +1,304 @@
+#include <format>
+#include <functional>
+#include <iostream>
+#include <optional>
+#include <source_location>
+#include <string>
+#include <vector>
+
+// Expect
+
+#define EXPECT_EQ(context, left, right)                                        \
+  (context).Expect((left) == (right), "#left == #right");
+
+#define EXPECT_NE(context, left, right)                                        \
+  (context).Expect((left) != (right), "#left != #right");
+
+#define EXPECT_LE(context, left, right)                                        \
+  (context).Expect((left) <= (right), "#left <= #right");
+
+#define EXPECT_GE(context, left, right)                                        \
+  (context).Expect((left) >= (right), "#left >= #right");
+
+#define EXPECT_LT(context, left, right)                                        \
+  (context).Expect((left) < (right), "#left < #right");
+
+#define EXPECT_GT(context, left, right)                                        \
+  (context).Expect((left) > (right), "#left > #right");
+
+// Require
+
+#define REQUIRE_EQ(context, left, right)                                       \
+  (context).Require((left) == (right), "#left == #right");
+
+#define REQUIRE_NE(context, left, right)                                       \
+  (context).Require((left) != (right), "#left != #right");
+
+#define REQUIRE_LE(context, left, right)                                       \
+  (context).Require((left) <= (right), "#left <= #right");
+
+#define REQUIRE_GE(context, left, right)                                       \
+  (context).Require((left) >= (right), "#left >= #right");
+
+#define REQUIRE_LT(context, left, right)                                       \
+  (context).Require((left) < (right), "#left < #right");
+
+#define REQUIRE_GT(context, left, right)                                       \
+  (context).Require((left) > (right), "#left > #right");
+
+//
+
+namespace utils {
+
+std::string to_string(const std::source_location &source_location);
+
+struct Pos {
+public:
+  struct Point {
+    size_t line;
+    size_t position;
+  };
+
+public:
+  Point start;
+  Point end;
+};
+
+class Log {
+  friend class Context;
+
+public:
+  enum Kind {
+    kSys,
+    kProc,
+  };
+
+  enum class Level : uint32_t { // NOTE: change to_string(Log::Level level) on
+                                // change
+    kDebug = 1,
+    kInfo = 3,
+    kImportant = 5,
+    kWarning = 7,
+    kError = 9,
+    kFatal = 11,
+  };
+
+  enum class Area {
+    kDefault,
+    kParse,
+    kIntepret,
+    // ...
+  };
+  struct Fragment {
+    // Fragment(std::string fragment) : fragment(fragment), color(kNone) {}
+
+    enum Color {
+      kNone,
+      kDebug,
+      kInfo,
+      kImportant,
+      kWarning,
+      kError,
+      kFatal,
+    };
+
+    std::string fragment;
+    Color color = kNone;
+
+    explicit operator std::string() {
+      return fragment; // TODO: +color
+    }
+  };
+  using Fragments = std::vector<Fragment>;
+
+  struct Message {
+    Fragments message;
+    Level level;
+    Area area = Area::kDefault;
+    std::optional<Pos> pos = {};
+    std::source_location source_location = std::source_location::current();
+  };
+
+  class Context {
+  public:
+    Context(
+        Log &log, Area area, Level default_level = Level::kInfo,
+        std::source_location source_location = std::source_location::current())
+        : log_(log), area_(area), default_level_(default_level),
+          function_(to_string(source_location)) {
+      log_.PushLog<kSys>({
+          .message = {{"Enter ", Fragment::kInfo}, {function_}},
+          .level = default_level_,
+      });
+    }
+
+    ~Context() {
+      log_.PushLog<kSys>({
+          .message = {{"Leave ", Fragment::kInfo}, {function_}},
+          .level = default_level_,
+      });
+    }
+
+    Context(const Context &log) = delete;
+    Context(Context &&log) = delete;
+
+    //
+
+    template <Kind K>
+    void LogWithLevel(Fragments message, Level level,
+                      std::optional<Pos> pos = {},
+                      std::source_location source_location =
+                          std::source_location::current()) {
+      log_.PushLog<K>({
+          .message = std::move(message),
+          .level = level,
+          .area = area_,
+          .pos = pos,
+          .source_location = source_location,
+      });
+    }
+
+    template <Kind K>
+    void Default(Fragments message, std::optional<Pos> pos = {},
+                 std::source_location source_location =
+                     std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), default_level_, pos, source_location);
+    }
+
+    template <Kind K>
+    void Debug(Fragments message, std::optional<Pos> pos = {},
+               std::source_location source_location =
+                   std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), Level::kDebug, pos, source_location);
+    }
+
+    template <Kind K>
+    void Info(Fragments message, std::optional<Pos> pos = {},
+              std::source_location source_location =
+                  std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), Level::kInfo, pos, source_location);
+    }
+
+    template <Kind K>
+    void Important(Fragments message, std::optional<Pos> pos = {},
+                   std::source_location source_location =
+                       std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), Level::kImportant, pos,
+                      source_location);
+    }
+
+    template <Kind K>
+    void Warning(Fragments message, std::optional<Pos> pos = {},
+                 std::source_location source_location =
+                     std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), Level::kWarning, pos,
+                      source_location);
+    }
+
+    template <Kind K>
+    void Error(Fragments message, std::optional<Pos> pos = {},
+               std::source_location source_location =
+                   std::source_location::current()) {
+      LogWithLevel<K>(std::move(message), Level::kError, pos, source_location);
+    }
+
+    template <Kind K>
+    void Fatal(Fragments message, std::optional<Pos> pos = {},
+               std::source_location source_location =
+                   std::source_location::current()) {
+      auto entity = Message{
+          .message = std::move(message),
+          .level = Level::kFatal,
+          .area = area_,
+          .pos = pos,
+          .source_location = source_location,
+      };
+
+      log_.PushLog<K>(entity);
+      throw entity;
+    }
+
+    //
+
+    template <Kind K>
+    bool Expect(bool condition, Fragments message, std::optional<Pos> pos = {},
+                std::source_location source_location =
+                    std::source_location::current()) {
+      message.insert(message.begin(),
+                     {.fragment = "Expected: ", .color = Fragment::kError});
+      if (condition) {
+        Error<K>(std::move(message), pos, source_location);
+      }
+      return condition;
+    }
+
+    template <Kind K>
+    bool Require(bool condition, Fragments message, std::optional<Pos> pos = {},
+                 std::source_location source_location =
+                     std::source_location::current()) {
+      message.insert(message.begin(),
+                     {.fragment = "Required: ", .color = Fragment::kError});
+      if (condition) {
+        Error<K>(std::move(message), pos, source_location);
+      }
+      return condition;
+    }
+
+  private:
+    Log &log_;
+    Area area_;
+    Level default_level_;
+    std::string function_;
+  };
+
+public:
+  Log(std::function<void(const Message &)> sys_hook,
+      std::function<void(const Message &)> proc_hook)
+      : sys{}, proc{}, sys_hook_(sys_hook), proc_hook_(proc_hook) {}
+
+  // TODO: proc logs
+
+private:
+  template <Kind K> void PushLog(Message message) {
+    static_assert(K == kSys or K == kProc);
+    switch (K) {
+    case kSys:
+      sys_hook_(message);
+      sys.push_back(std::move(message));
+      break;
+    case kProc:
+      proc_hook_(message);
+      proc.push_back(std::move(message));
+      break;
+    }
+  }
+
+private:
+  std::vector<Message> sys; // logs for runing code
+  std::vector<Message>
+      proc; // logs for code parsing / type check / interpretation / ...
+  std::function<void(const Message &)> sys_hook_;
+  std::function<void(const Message &)> proc_hook_;
+};
+
+//
+
+std::string to_string(const std::source_location &source_location);
+
+std::string to_string(Pos::Point point);
+
+std::string to_string(Pos pos);
+
+std::string to_string(Log::Fragments fragments);
+
+std::string to_string(Log::Level level);
+
+std::string to_string(Log::Message message);
+
+//
+
+Log BuildPrintLog(std::ostream &out, Log::Level min_level = Log::Level::kInfo);
+
+} // namespace utils
+
+using utils::Log;
diff --git a/lang/utils/src/executor.cpp b/lang/utils/src/executor.cpp
new file mode 100644
index 0000000..e4390e4
--- /dev/null
+++ b/lang/utils/src/executor.cpp
@@ -0,0 +1 @@
+#include "executor.hpp"
diff --git a/lang/utils/src/log.cpp b/lang/utils/src/log.cpp
new file mode 100644
index 0000000..6189aaf
--- /dev/null
+++ b/lang/utils/src/log.cpp
@@ -0,0 +1,54 @@
+#include "log.hpp"
+
+#include "magic_enum.hpp"
+
+#include <numeric>
+
+namespace utils {
+
+std::string to_string(const std::source_location &source_location) {
+  return std::format("{}:{} {}", source_location.file_name(),
+                     source_location.line(), source_location.function_name());
+}
+
+std::string to_string(Pos::Point point) {
+  return std::format("{},{}", point.line, point.position);
+}
+
+std::string to_string(Pos pos) {
+  return std::format("{} - {}", to_string(pos.start), to_string(pos.end));
+}
+
+std::string to_string(Log::Fragments fragments) {
+  return std::accumulate( //
+      std::move_iterator(fragments.begin()),
+      std::move_iterator(fragments.end()), std::string{},
+      [](auto &&acc, Log::Fragment &&fragment) {
+        acc += static_cast<std::string>(fragment);
+        return acc;
+      });
+}
+
+std::string to_string(Log::Level level) {
+  return std::string{magic_enum::enum_name(level).substr(1)}; // k... -> ...
+}
+
+std::string to_string(Log::Message message) {
+  return std::format(
+      "{}: {}{} ({})", to_string(message.level), to_string(message.message),
+      message.pos ? (" at " + to_string(*message.pos)) : std::string{},
+      to_string(message.source_location));
+}
+
+//
+
+inline Log BuildPrintLog(std::ostream &out, Log::Level min_level) {
+  auto const print = [&out, min_level](const Log::Message &message) {
+    if (message.level >= min_level) {
+      out << to_string(message);
+    }
+  };
+  return Log(print, print);
+}
+
+} // namespace utils
diff --git a/lang/utils/xmake.lua b/lang/utils/xmake.lua
index 15a7127..8850e50 100644
--- a/lang/utils/xmake.lua
+++ b/lang/utils/xmake.lua
@@ -1,8 +1,15 @@
 set_languages("c++20")
 
+add_requires("magic_enum")
+
+-- TODO:
+-- includes("../../deps/termcolor")
+
 target("lang.utils")
     set_kind("static")
     add_includedirs("include", {public = true})
     add_files("src/**.cpp")
+    add_packages("magic_enum")
+    -- add_deps("termcolor")
     set_warnings("allextra", "error")
     set_rundir("$(projectdir)")