diff --git a/src/Lib/Core.php b/src/Lib/Core.php
new file mode 100644
index 0000000..94d3349
--- /dev/null
+++ b/src/Lib/Core.php
@@ -0,0 +1,114 @@
+<?php
+namespace MadLisp\Lib;
+
+use MadLisp\Collection;
+use MadLisp\CoreFunc;
+use MadLisp\Env;
+use MadLisp\Evaller;
+use MadLisp\Func;
+use MadLisp\MadLispException;
+use MadLisp\MList;
+use MadLisp\Printer;
+use MadLisp\Reader;
+use MadLisp\Symbol;
+use MadLisp\Tokenizer;
+use MadLisp\UserFunc;
+
+class Core implements ILib
+{
+    protected Tokenizer $tokenizer;
+    protected Reader $reader;
+    protected Printer $printer;
+    protected Evaller $evaller;
+
+    public function __construct(Tokenizer $tokenizer, Reader $reader, Printer $printer, Evaller $evaller)
+    {
+        $this->tokenizer = $tokenizer;
+        $this->reader = $reader;
+        $this->printer = $printer;
+        $this->evaller = $evaller;
+    }
+
+    public function register(Env $env): void
+    {
+        // Register special constants
+        $env->set('__FILE__', null);
+        $env->set('__DIR__', null);
+
+        $env->set('debug', new CoreFunc('debug', 'Toggle debug mode.', 0, 0,
+            function () {
+                $val = !$this->evaller->getDebug();
+                $this->evaller->setDebug($val);
+                return $val;
+            }
+        ));
+
+        $env->set('doc', new CoreFunc('doc', 'Get documentation for a function.', 1, 1,
+            function ($a) {
+                if ($a instanceof Func) {
+                    return $a->getDoc();
+                }
+
+                throw new MadLispException('first argument to doc is not function');
+            }
+        ));
+
+        $env->set('loop', new CoreFunc('loop', 'Call the given function repeatedly in a loop until it returns false.', 1, -1,
+            function (Func $f, ...$args) {
+                do {
+                    $result = $f->call($args);
+                } while ($result);
+                return $result;
+            }
+        ));
+
+        $env->set('meta', new CoreFunc('meta', 'Read meta information of an entity.', 2, 2,
+            function ($obj, $attribute) {
+                if ($obj instanceof Env) {
+                    if ($attribute == 'name') {
+                        return $obj->getFullName();
+                    } elseif ($attribute == 'parent') {
+                        return $obj->getParent();
+                    } else {
+                        throw new MadLispException('unknown attribute for meta');
+                    }
+                } elseif ($obj instanceof UserFunc) {
+                    if ($attribute == 'args') {
+                        return $obj->getBindings();
+                    } elseif ($attribute == 'body') {
+                        return $obj->getAst();
+                    } elseif ($attribute == 'code') {
+                        return new MList([new Symbol('fn'), $obj->getBindings(), $obj->getAst()]);
+                    } else {
+                        throw new MadLispException('unknown attribute for meta');
+                    }
+                } else {
+                    throw new MadLispException('unknown entity for meta');
+                }
+            }
+        ));
+
+        $env->set('read', new CoreFunc('read', 'Read string as code.', 1, 1,
+            fn (string $a) => $this->reader->read($this->tokenizer->tokenize($a))
+        ));
+
+        $env->set('print', new CoreFunc('print', 'Print argument. Give second argument as true to show strings in readable format.', 1, 2,
+            function ($a, bool $readable = false) {
+                $this->printer->print($a, $readable);
+                return null;
+            }
+        ));
+
+        $env->set('error', new CoreFunc('error', 'Throw an exception using argument (string) as message.', 1, 1,
+            function (string $error) {
+                throw new MadLispException($error);
+            }
+        ));
+
+        $env->set('exit', new CoreFunc('exit', 'Terminate the script with given exit code.', 0, 1,
+            function (int $status = 0) {
+                exit($status);
+            }
+        ));
+    }
+}
diff --git a/src/LispFactory.php b/src/LispFactory.php
index d0308fb..484863e 100644
--- a/src/LispFactory.php
+++ b/src/LispFactory.php
@@ -13,86 +13,8 @@ class LispFactory
         // Root environment
         $env = new Env('root');
 
-        // Register special constants
-        $env->set('__FILE__', null);
-        $env->set('__DIR__', null);
-
         // Register core functions
-        $env->set('debug', new CoreFunc('debug', 'Toggle debug mode.', 0, 0,
-            function () use ($eval) {
-                $val = !$eval->getDebug();
-                $eval->setDebug($val);
-                return $val;
-            }
-        ));
-
-        $env->set('doc', new CoreFunc('doc', 'Get documentation for a function.', 1, 1,
-            function ($a) {
-                if ($a instanceof Func) {
-                    return $a->getDoc();
-                }
-
-                throw new MadLispException('first argument to doc is not function');
-            }
-        ));
-
-        $env->set('loop', new CoreFunc('loop', 'Call the given function repeatedly in a loop until it returns false.', 1, -1,
-            function (Func $f, ...$args) {
-                do {
-                    $result = $f->call($args);
-                } while ($result);
-                return $result;
-            }
-        ));
-
-        $env->set('meta', new CoreFunc('meta', 'Read meta information of an entity.', 2, 2,
-            function ($obj, $attribute) {
-                if ($obj instanceof Env) {
-                    if ($attribute == 'name') {
-                        return $obj->getFullName();
-                    } elseif ($attribute == 'parent') {
-                        return $obj->getParent();
-                    } else {
-                        throw new MadLispException('unknown attribute for meta');
-                    }
-                } elseif ($obj instanceof UserFunc) {
-                    if ($attribute == 'args') {
-                        return $obj->getBindings();
-                    } elseif ($attribute == 'body') {
-                        return $obj->getAst();
-                    } elseif ($attribute == 'code') {
-                        return new MList([new Symbol('fn'), $obj->getBindings(), $obj->getAst()]);
-                    } else {
-                        throw new MadLispException('unknown attribute for meta');
-                    }
-                } else {
-                    throw new MadLispException('unknown entity for meta');
-                }
-            }
-        ));
-
-        $env->set('read', new CoreFunc('read', 'Read string as code.', 1, 1,
-            fn (string $a) => $reader->read($tokenizer->tokenize($a))
-        ));
-
-        $env->set('print', new CoreFunc('print', 'Print argument. Give second argument as true to show strings in readable format.', 1, 2,
-            function ($a, bool $readable = false) use ($printer) {
-                $printer->print($a, $readable);
-                return null;
-            }
-        ));
-
-        $env->set('error', new CoreFunc('error', 'Throw an exception using argument (string) as message.', 1, 1,
-            function (string $error) {
-                throw new MadLispException($error);
-            }
-        ));
-
-        $env->set('exit', new CoreFunc('exit', 'Terminate the script with given exit code.', 0, 1,
-            function (int $status = 0) {
-                exit($status);
-            }
-        ));
+        (new Lib\Core($tokenizer, $reader, $printer, $eval))->register($env);
 
         // Register core libraries
         (new Lib\Collections())->register($env);