diff --git a/bootstrap.php b/bootstrap.php
index 237f3cc..e8aec54 100644
--- a/bootstrap.php
+++ b/bootstrap.php
@@ -16,6 +16,7 @@ function ml_get_lisp(): array
 
     (new MadLisp\Lib\Math())->register($env);
     (new MadLisp\Lib\Compare())->register($env);
+    (new MadLisp\Lib\Types())->register($env);
 
     /*
     $env->set('eval', function (...$args) use ($eval, $env) {
diff --git a/src/Lib/Core.php b/src/Lib/Core.php
deleted file mode 100644
index 906773b..0000000
--- a/src/Lib/Core.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-namespace MadLisp\Lib;
-
-use MadLisp\Env;
-use MadLisp\Func;
-use MadLisp\Hash;
-use MadLisp\MadLispException;
-use MadLisp\MList;
-use MadLisp\Symbol;
-use MadLisp\Util;
-
-class Core implements ILib
-{
-    public function register(Env $env): void
-    {
-        // types
-
-        $env->set('type?', function ($a) {
-            if ($a instanceof Func) {
-                return 'function';
-            } elseif ($a instanceof MList) {
-                return 'list';
-            } elseif ($a instanceof Hash) {
-                return 'hash';
-            } elseif ($a instanceof Symbol) {
-                return 'symbol';
-            } elseif ($a === true || $a === false) {
-                return 'bool';
-            } elseif ($a === null) {
-                return 'null';
-            } elseif (is_int($a)) {
-                return 'int';
-            } elseif (is_float($a)) {
-                return 'float';
-            } else {
-                return 'string';
-            }
-        });
-
-        $env->set('fn?', fn ($a) => $a instanceof Func);
-        $env->set('list?', fn ($a) => $a instanceof MList);
-        $env->set('hash?', fn ($a) => $a instanceof Hash);
-        $env->set('sym?', fn ($a) => $a instanceof Symbol);
-        $env->set('bool?', fn ($a) => $a === true || $a === false);
-        $env->set('true?', fn ($a) => $a == true); // not strict
-        $env->set('false?', fn ($a) => $a == false); // not strict
-        $env->set('null?', fn ($a) => $a === null);
-        $env->set('int?', fn ($a) => is_int($a));
-        $env->set('float?', fn ($a) => is_float($a));
-        $env->set('str?', fn ($a) => is_string($a));
-
-    }
-}
diff --git a/src/Lib/Types.php b/src/Lib/Types.php
new file mode 100644
index 0000000..d723c48
--- /dev/null
+++ b/src/Lib/Types.php
@@ -0,0 +1,97 @@
+<?php
+namespace MadLisp\Lib;
+
+use MadLisp\CoreFunc;
+use MadLisp\Env;
+use MadLisp\Hash;
+use MadLisp\Func;
+use MadLisp\MList;
+use MadLisp\Seq;
+use MadLisp\Symbol;
+use MadLisp\Vector;
+
+class Types implements ILib
+{
+    public function register(Env $env): void
+    {
+        // Test types
+
+        $env->set('type?', new CoreFunc('type?', 'Return the type of argument as a string.', 1, 1,
+            function ($a) {
+                if ($a instanceof Func) {
+                    return 'function';
+                } elseif ($a instanceof MList) {
+                    return 'list';
+                } elseif ($a instanceof Vector) {
+                    return 'vector';
+                } elseif ($a instanceof Hash) {
+                    return 'hash';
+                } elseif ($a instanceof Symbol) {
+                    return 'symbol';
+                } elseif ($a === true || $a === false) {
+                    return 'bool';
+                } elseif ($a === null) {
+                    return 'null';
+                } elseif (is_int($a)) {
+                    return 'int';
+                } elseif (is_float($a)) {
+                    return 'float';
+                } else {
+                    return 'string';
+                }
+            }
+        ));
+
+        $env->set('fn?', new CoreFunc('fn?', 'Return true if argument is a function.', 1, 1,
+            fn ($a) => $a instanceof Func
+        ));
+
+        $env->set('list?', new CoreFunc('list?', 'Return true if argument is a list.', 1, 1,
+            fn ($a) => $a instanceof MList
+        ));
+
+        $env->set('vector?', new CoreFunc('vector?', 'Return true if argument is a vector.', 1, 1,
+            fn ($a) => $a instanceof Vector
+        ));
+
+        $env->set('seq?', new CoreFunc('seq?', 'Return true if argument is a list or a vector.', 1, 1,
+            fn ($a) => $a instanceof Seq
+        ));
+
+        $env->set('hash?', new CoreFunc('hash?', 'Return true if argument is a hash map.', 1, 1,
+            fn ($a) => $a instanceof Hash
+        ));
+
+        $env->set('symbol?', new CoreFunc('symbol?', 'Return true if argument is a symbol.', 1, 1,
+            fn ($a) => $a instanceof Symbol
+        ));
+
+        $env->set('bool?', new CoreFunc('bool?', 'Return true if argument is a boolean.', 1, 1,
+            fn ($a) => $a === true || $a === false
+        ));
+
+        $env->set('true?', new CoreFunc('true?', 'Return true if argument evaluates to true.', 1, 1,
+            fn ($a) => $a == true // not strict
+        ));
+
+        $env->set('false?', new CoreFunc('false?', 'Return true if argument evaluates to false.', 1, 1,
+            fn ($a) => $a == false // not strict
+        ));
+
+        $env->set('null?', new CoreFunc('null?', 'Return true if argument is null.', 1, 1,
+            fn ($a) => $a === null
+        ));
+
+        $env->set('int?', new CoreFunc('int?', 'Return true if argument is an integer.', 1, 1,
+            fn ($a) => is_int($a)
+        ));
+
+        $env->set('float?', new CoreFunc('float?', 'Return true if argument is a float.', 1, 1,
+            fn ($a) => is_float($a)
+        ));
+
+        $env->set('str?', new CoreFunc('str?', 'Return true if argument is a string.', 1, 1,
+            fn ($a) => is_string($a)
+        ));
+    }
+}