diff --git a/include/pocketpy/interpreter/typeinfo.h b/include/pocketpy/interpreter/typeinfo.h
index 958ff3a1..340920fc 100644
--- a/include/pocketpy/interpreter/typeinfo.h
+++ b/include/pocketpy/interpreter/typeinfo.h
@@ -4,10 +4,9 @@
 #include "pocketpy/common/vector.h"
 #include "pocketpy/objects/object.h"
 
-#define PK_MAX_CHUNK_LENGTH 256
-
 typedef struct py_TypeInfo {
     py_Name name;
+    py_Type index;
     py_Type base;
     struct py_TypeInfo* base_ti;
 
@@ -17,20 +16,13 @@ typedef struct py_TypeInfo {
     bool is_python;  // is it a python class? (not derived from c object)
     bool is_sealed;  // can it be subclassed?
 
-    void (*dtor)(void*);
+    py_Dtor dtor;  // destructor for this type, NULL if no dtor
 
     py_TValue annotations;
 
     void (*on_end_subclass)(struct py_TypeInfo*);  // backdoor for enum module
 } py_TypeInfo;
 
-typedef struct TypeList {
-    int length;
-    py_TypeInfo* chunks[PK_MAX_CHUNK_LENGTH];
-} TypeList;
-
-void TypeList__ctor(TypeList* self);
-void TypeList__dtor(TypeList* self);
-py_TypeInfo* TypeList__get(TypeList* self, py_Type index);
-py_TypeInfo* TypeList__emplace(TypeList* self);
-void TypeList__apply(TypeList* self, void (*f)(py_TypeInfo*, void*), void* ctx);
+py_TypeInfo* pk_typeinfo(py_Type type);
+py_ItemRef pk_tpfindname(py_TypeInfo* ti, py_Name name);
+#define pk_tpfindmagic pk_tpfindname
\ No newline at end of file
diff --git a/include/pocketpy/interpreter/vm.h b/include/pocketpy/interpreter/vm.h
index 61c30880..3592fea5 100644
--- a/include/pocketpy/interpreter/vm.h
+++ b/include/pocketpy/interpreter/vm.h
@@ -29,11 +29,16 @@ typedef struct WatchdogInfo {
     clock_t max_reset_time;
 } WatchdogInfo;
 
+typedef struct TypePointer {
+    py_TypeInfo* ti;
+    py_Dtor dtor;
+} TypePointer;
+
 typedef struct VM {
     py_Frame* top_frame;
 
     BinTree modules;
-    TypeList types;
+    c11_vector /*TypePointer*/ types;
 
     py_GlobalRef builtins;  // builtins module
     py_GlobalRef main;      // __main__ module
@@ -80,7 +85,7 @@ bool pk__parse_int_slice(py_Ref slice,
 bool pk__normalize_index(int* index, int length);
 
 bool pk__object_new(int argc, py_Ref argv);
-py_TypeInfo* pk__type_info(py_Type type);
+py_TypeInfo* pk_typeinfo(py_Type type);
 
 bool pk_wrapper__self(int argc, py_Ref argv);
 
diff --git a/src/interpreter/ceval.c b/src/interpreter/ceval.c
index cf355cd0..5c391e40 100644
--- a/src/interpreter/ceval.c
+++ b/src/interpreter/ceval.c
@@ -1036,7 +1036,7 @@ FrameResult VM__run_top_frame(VM* self) {
                 }
                 POP();
 
-                py_TypeInfo* base_ti = TypeList__get(&self->types, base);
+                py_TypeInfo* base_ti = pk_typeinfo(base);
                 if(base_ti->is_sealed) {
                     TypeError("type '%t' is not an acceptable base type", base);
                     goto __ERROR;
@@ -1059,7 +1059,7 @@ FrameResult VM__run_top_frame(VM* self) {
 
                 if(py_istype(TOP(), tp_type)) {
                     // call on_end_subclass
-                    py_TypeInfo* ti = TypeList__get(&self->types, py_totype(TOP()));
+                    py_TypeInfo* ti = py_touserdata(TOP());
                     if(ti->base != tp_object) {
                         py_TypeInfo* base_ti = ti->base_ti;
                         if(base_ti->on_end_subclass) base_ti->on_end_subclass(ti);
@@ -1096,8 +1096,7 @@ FrameResult VM__run_top_frame(VM* self) {
             case OP_ADD_CLASS_ANNOTATION: {
                 assert(self->curr_class);
                 // [type_hint string]
-                py_Type type = py_totype(self->curr_class);
-                py_TypeInfo* ti = TypeList__get(&self->types, type);
+                py_TypeInfo* ti = py_touserdata(self->curr_class);
                 if(py_isnil(&ti->annotations)) py_newdict(&ti->annotations);
                 py_Name name = co_names[byte.arg];
                 bool ok = py_dict_setitem_by_str(&ti->annotations, py_name2str(name), TOP());
diff --git a/src/interpreter/typeinfo.c b/src/interpreter/typeinfo.c
index 7d352ae6..db543c01 100644
--- a/src/interpreter/typeinfo.c
+++ b/src/interpreter/typeinfo.c
@@ -1,51 +1,49 @@
-#include "pocketpy/interpreter/typeinfo.h"
-#include "pocketpy/common/utils.h"
+#include "pocketpy/interpreter/vm.h"
 
-#define CHUNK_SIZE 128
-#define LOG2_CHUNK_SIZE 7
-
-void TypeList__ctor(TypeList* self) {
-    self->length = 0;
-    memset(self->chunks, 0, sizeof(self->chunks));
+py_ItemRef pk_tpfindname(py_TypeInfo* ti, py_Name name) {
+    assert(ti != NULL);
+    do {
+        py_Ref res = py_getdict(&ti->self, name);
+        if(res) return res;
+        ti = ti->base_ti;
+    } while(ti);
+    return NULL;
 }
 
-void TypeList__dtor(TypeList* self) {
-    for(py_Type t = 0; t < self->length; t++) {
-        py_TypeInfo* info = TypeList__get(self, t);
-        (void)info;
-    }
-    for(int i = 0; i < PK_MAX_CHUNK_LENGTH; i++) {
-        if(self->chunks[i]) PK_FREE(self->chunks[i]);
-    }
+py_ItemRef py_tpfindname(py_Type type, py_Name name) {
+    py_TypeInfo* ti = pk_typeinfo(type);
+    return pk_tpfindname(ti, name);
 }
 
-py_TypeInfo* TypeList__get(TypeList* self, py_Type index) {
-    assert(index < self->length);
-    int chunk = index >> LOG2_CHUNK_SIZE;
-    int offset = index & (CHUNK_SIZE - 1);
-    return self->chunks[chunk] + offset;
+py_Ref py_tpfindmagic(py_Type t, py_Name name) {
+    // assert(py_ismagicname(name));
+    return py_tpfindname(t, name);
 }
 
-py_TypeInfo* TypeList__emplace(TypeList* self) {
-    int chunk = self->length >> LOG2_CHUNK_SIZE;
-    int offset = self->length & (CHUNK_SIZE - 1);
-    if(self->chunks[chunk] == NULL) {
-        if(chunk >= PK_MAX_CHUNK_LENGTH) {
-            c11__abort("TypeList__emplace(): max chunk length exceeded");
-        }
-        self->chunks[chunk] = PK_MALLOC(sizeof(py_TypeInfo) * CHUNK_SIZE);
-        memset(self->chunks[chunk], 0, sizeof(py_TypeInfo) * CHUNK_SIZE);
-    }
-    self->length++;
-    return self->chunks[chunk] + offset;
+py_Type py_tpbase(py_Type t) {
+    assert(t);
+    py_TypeInfo* ti = pk_typeinfo(t);
+    return ti->base;
 }
 
-void TypeList__apply(TypeList* self, void (*f)(py_TypeInfo*, void*), void* ctx) {
-    for(int i = 0; i < self->length; i++) {
-        py_TypeInfo* info = TypeList__get(self, i);
-        f(info, ctx);
-    }
+PK_DEPRECATED py_Ref py_tpgetmagic(py_Type type, py_Name name) {
+    // assert(py_ismagicname(name));
+    py_TypeInfo* ti = pk_typeinfo(type);
+    py_Ref retval = py_getdict(&ti->self, name);
+    return retval != NULL ? retval : py_NIL();
 }
 
-#undef CHUNK_SIZE
-#undef LOG2_CHUNK_SIZE
\ No newline at end of file
+py_Ref py_tpobject(py_Type type) {
+    assert(type);
+    return &pk_typeinfo(type)->self;
+}
+
+const char* py_tpname(py_Type type) {
+    if(!type) return "nil";
+    py_Name name = pk_typeinfo(type)->name;
+    return py_name2str(name);
+}
+
+py_TypeInfo* pk_typeinfo(py_Type type) {
+    return c11__getitem(TypePointer, &pk_current_vm->types, type).ti;
+}
\ No newline at end of file
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index 952e873b..fa3771fa 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -39,40 +39,12 @@ void LineProfiler__tracefunc(py_Frame* frame, enum py_TraceEvent event) {
     if(self->enabled && event == TRACE_EVENT_LINE) { LineProfiler__tracefunc_line(self, frame); }
 }
 
-static void py_TypeInfo__ctor(py_TypeInfo* self,
-                              py_Name name,
-                              py_Type index,
-                              py_Type base,
-                              py_TypeInfo* base_ti,
-                              py_GlobalRef module) {
-    memset(self, 0, sizeof(py_TypeInfo));
-
-    self->name = name;
-    self->base = base;
-    self->base_ti = base_ti;
-
-    // create type object with __dict__
-    ManagedHeap* heap = &pk_current_vm->heap;
-    PyObject* typeobj = ManagedHeap__new(heap, tp_type, -1, sizeof(py_Type));
-    *(py_Type*)PyObject__userdata(typeobj) = index;
-    self->self = (py_TValue){
-        .type = typeobj->type,
-        .is_ptr = true,
-        ._obj = typeobj,
-    };
-
-    self->module = module;
-    self->annotations = *py_NIL();
-}
-
 static int BinTree__cmp_cstr(void* lhs, void* rhs) {
     const char* l = (const char*)lhs;
     const char* r = (const char*)rhs;
     return strcmp(l, r);
 }
 
-static int BinTree__cmp_voidp(void* lhs, void* rhs) { return lhs < rhs ? -1 : (lhs > rhs ? 1 : 0); }
-
 void VM__ctor(VM* self) {
     self->top_frame = NULL;
 
@@ -81,7 +53,7 @@ void VM__ctor(VM* self) {
         .need_free_key = true,
     };
     BinTree__ctor(&self->modules, c11_strdup(""), py_NIL(), &modules_config);
-    TypeList__ctor(&self->types);
+    c11_vector__ctor(&self->types, sizeof(TypePointer));
 
     self->builtins = NULL;
     self->main = NULL;
@@ -116,14 +88,15 @@ void VM__ctor(VM* self) {
 
     /* Init Builtin Types */
     // 0: unused
-    void* placeholder = TypeList__emplace(&self->types);
-    memset(placeholder, 0, sizeof(py_TypeInfo));
+    TypePointer* placeholder = c11_vector__emplace(&self->types);
+    placeholder->ti = NULL;
+    placeholder->dtor = NULL;
 
 #define validate(t, expr)                                                                          \
     if(t != (expr)) abort()
 
-    validate(tp_object, pk_newtype("object", 0, NULL, NULL, true, false));
-    validate(tp_type, pk_newtype("type", 1, NULL, NULL, false, true));
+    validate(tp_object, pk_newtype("object", tp_nil, NULL, NULL, true, false));
+    validate(tp_type, pk_newtype("type", tp_object, NULL, NULL, false, true));
     pk_object__register();
 
     validate(tp_int, pk_newtype("int", tp_object, NULL, NULL, false, true));
@@ -229,7 +202,7 @@ void VM__ctor(VM* self) {
     };
 
     for(int i = 0; i < c11__count_array(public_types); i++) {
-        py_TypeInfo* ti = pk__type_info(public_types[i]);
+        py_TypeInfo* ti = pk_typeinfo(public_types[i]);
         py_setdict(self->builtins, ti->name, &ti->self);
     }
 
@@ -287,7 +260,7 @@ void VM__dtor(VM* self) {
     while(self->top_frame)
         VM__pop_frame(self);
     BinTree__dtor(&self->modules);
-    TypeList__dtor(&self->types);
+    c11_vector__dtor(&self->types);
     FixedMemoryPool__dtor(&self->pool_frame);
     ValueStack__dtor(&self->stack);
     CachedNames__dtor(&self->cached_names);
@@ -398,16 +371,30 @@ py_Type pk_newtype(const char* name,
                    bool is_python,
                    bool is_sealed) {
     py_Type index = pk_current_vm->types.length;
-    py_TypeInfo* ti = TypeList__emplace(&pk_current_vm->types);
-    py_TypeInfo* base_ti = base ? pk__type_info(base) : NULL;
+    py_TypeInfo* self = py_newobject(py_retval(), tp_type, -1, sizeof(py_TypeInfo));
+    py_TypeInfo* base_ti = base ? pk_typeinfo(base) : NULL;
     if(base_ti && base_ti->is_sealed) {
         c11__abort("type '%s' is not an acceptable base type", py_name2str(base_ti->name));
     }
-    py_TypeInfo__ctor(ti, py_name(name), index, base, base_ti, module ? module : py_NIL());
+
+    memset(self, 0, sizeof(py_TypeInfo));
+    self->name = py_name(name);
+    self->index = index;
+    self->base = base;
+    self->base_ti = base_ti;
+
+    self->self = *py_retval();
+    self->module = module ? module : py_NIL();
+    self->annotations = *py_NIL();
+
     if(!dtor && base) dtor = base_ti->dtor;
-    ti->dtor = dtor;
-    ti->is_python = is_python;
-    ti->is_sealed = is_sealed;
+    self->is_python = is_python;
+    self->is_sealed = is_sealed;
+    self->dtor = dtor;
+
+    TypePointer* pointer = c11_vector__emplace(&pk_current_vm->types);
+    pointer->ti = self;
+    pointer->dtor = dtor;
     return index;
 }
 
@@ -628,12 +615,6 @@ FrameResult VM__vectorcall(VM* self, uint16_t argc, uint16_t kwargc, bool opcall
 }
 
 /****************************************/
-void PyObject__dtor(PyObject* self) {
-    py_TypeInfo* ti = pk__type_info(self->type);
-    if(ti->dtor) ti->dtor(PyObject__userdata(self));
-    if(self->slots == -1) NameDict__dtor(PyObject__dict(self));
-}
-
 void FuncDecl__gc_mark(const FuncDecl* self, c11_vector* p_stack) {
     CodeObject__gc_mark(&self->code, p_stack);
     for(int j = 0; j < self->kwargs.length; j++) {
@@ -684,10 +665,8 @@ void ManagedHeap__mark(ManagedHeap* self) {
     int types_length = vm->types.length;
     // 0-th type is placeholder
     for(py_Type i = 1; i < types_length; i++) {
-        py_TypeInfo* ti = TypeList__get(&vm->types, i);
-        // mark type object
+        py_TypeInfo* ti = c11__getitem(TypePointer, &vm->types, i).ti;
         pk__mark_value(&ti->self);
-        // mark type annotations
         pk__mark_value(&ti->annotations);
     }
     // mark frame
@@ -763,125 +742,3 @@ void ManagedHeap__mark(ManagedHeap* self) {
         }
     }
 }
-
-void pk_print_stack(VM* self, py_Frame* frame, Bytecode byte) {
-    return;
-    if(frame == NULL || py_isnil(self->main)) return;
-
-    py_TValue* sp = self->stack.sp;
-    c11_sbuf buf;
-    c11_sbuf__ctor(&buf);
-    for(py_Ref p = self->stack.begin; p != sp; p++) {
-        switch(p->type) {
-            case tp_nil: c11_sbuf__write_cstr(&buf, "nil"); break;
-            case tp_int: c11_sbuf__write_i64(&buf, p->_i64); break;
-            case tp_float: c11_sbuf__write_f64(&buf, p->_f64, -1); break;
-            case tp_bool: c11_sbuf__write_cstr(&buf, p->_bool ? "True" : "False"); break;
-            case tp_NoneType: c11_sbuf__write_cstr(&buf, "None"); break;
-            case tp_list: {
-                pk_sprintf(&buf, "list(%d)", py_list_len(p));
-                break;
-            }
-            case tp_tuple: {
-                pk_sprintf(&buf, "tuple(%d)", py_tuple_len(p));
-                break;
-            }
-            case tp_function: {
-                Function* ud = py_touserdata(p);
-                c11_sbuf__write_cstr(&buf, ud->decl->code.name->data);
-                c11_sbuf__write_cstr(&buf, "()");
-                break;
-            }
-            case tp_type: {
-                pk_sprintf(&buf, "<class '%t'>", py_totype(p));
-                break;
-            }
-            case tp_str: {
-                pk_sprintf(&buf, "%q", py_tosv(p));
-                break;
-            }
-            case tp_module: {
-                py_Ref path = py_getdict(p, __path__);
-                pk_sprintf(&buf, "<module '%v'>", py_tosv(path));
-                break;
-            }
-            default: {
-                pk_sprintf(&buf, "(%t)", p->type);
-                break;
-            }
-        }
-        if(p != &sp[-1]) c11_sbuf__write_cstr(&buf, ", ");
-    }
-    c11_string* stack_str = c11_sbuf__submit(&buf);
-
-    printf("%s:%-3d: %-25s %-6d [%s]\n",
-           frame->co->src->filename->data,
-           Frame__lineno(frame),
-           pk_opname(byte.op),
-           byte.arg,
-           stack_str->data);
-    c11_string__delete(stack_str);
-}
-
-bool pk_wrapper__self(int argc, py_Ref argv) {
-    PY_CHECK_ARGC(1);
-    py_assign(py_retval(), argv);
-    return true;
-}
-
-py_TypeInfo* pk__type_info(py_Type type) { return TypeList__get(&pk_current_vm->types, type); }
-
-int py_replinput(char* buf, int max_size) {
-    buf[0] = '\0';  // reset first char because we check '@' at the beginning
-
-    int size = 0;
-    bool multiline = false;
-    printf(">>> ");
-
-    while(true) {
-        int c = pk_current_vm->callbacks.getchr();
-        if(c == EOF) return -1;
-
-        if(c == '\n') {
-            char last = '\0';
-            if(size > 0) last = buf[size - 1];
-            if(multiline) {
-                if(last == '\n') {
-                    break;  // 2 consecutive newlines to end multiline input
-                } else {
-                    printf("... ");
-                }
-            } else {
-                if(last == ':' || last == '(' || last == '[' || last == '{' || buf[0] == '@') {
-                    printf("... ");
-                    multiline = true;
-                } else {
-                    break;
-                }
-            }
-        }
-
-        if(size == max_size - 1) {
-            buf[size] = '\0';
-            return size;
-        }
-
-        buf[size++] = c;
-    }
-
-    buf[size] = '\0';
-    return size;
-}
-
-py_Ref py_name2ref(py_Name name) {
-    assert(name != NULL);
-    CachedNames* d = &pk_current_vm->cached_names;
-    py_Ref res = CachedNames__try_get(d, name);
-    if(res != NULL) return res;
-    // not found, create a new one
-    py_StackRef tmp = py_pushtmp();
-    py_newstrv(tmp, py_name2sv(name));
-    CachedNames__set(d, name, tmp);
-    py_pop();
-    return CachedNames__try_get(d, name);
-}
\ No newline at end of file
diff --git a/src/interpreter/vmx.c b/src/interpreter/vmx.c
new file mode 100644
index 00000000..e9b25876
--- /dev/null
+++ b/src/interpreter/vmx.c
@@ -0,0 +1,127 @@
+#include "pocketpy/interpreter/vm.h"
+
+void pk_print_stack(VM* self, py_Frame* frame, Bytecode byte) {
+    return;
+    if(frame == NULL || py_isnil(self->main)) return;
+
+    py_TValue* sp = self->stack.sp;
+    c11_sbuf buf;
+    c11_sbuf__ctor(&buf);
+    for(py_Ref p = self->stack.begin; p != sp; p++) {
+        switch(p->type) {
+            case tp_nil: c11_sbuf__write_cstr(&buf, "nil"); break;
+            case tp_int: c11_sbuf__write_i64(&buf, p->_i64); break;
+            case tp_float: c11_sbuf__write_f64(&buf, p->_f64, -1); break;
+            case tp_bool: c11_sbuf__write_cstr(&buf, p->_bool ? "True" : "False"); break;
+            case tp_NoneType: c11_sbuf__write_cstr(&buf, "None"); break;
+            case tp_list: {
+                pk_sprintf(&buf, "list(%d)", py_list_len(p));
+                break;
+            }
+            case tp_tuple: {
+                pk_sprintf(&buf, "tuple(%d)", py_tuple_len(p));
+                break;
+            }
+            case tp_function: {
+                Function* ud = py_touserdata(p);
+                c11_sbuf__write_cstr(&buf, ud->decl->code.name->data);
+                c11_sbuf__write_cstr(&buf, "()");
+                break;
+            }
+            case tp_type: {
+                pk_sprintf(&buf, "<class '%t'>", py_totype(p));
+                break;
+            }
+            case tp_str: {
+                pk_sprintf(&buf, "%q", py_tosv(p));
+                break;
+            }
+            case tp_module: {
+                py_Ref path = py_getdict(p, __path__);
+                pk_sprintf(&buf, "<module '%v'>", py_tosv(path));
+                break;
+            }
+            default: {
+                pk_sprintf(&buf, "(%t)", p->type);
+                break;
+            }
+        }
+        if(p != &sp[-1]) c11_sbuf__write_cstr(&buf, ", ");
+    }
+    c11_string* stack_str = c11_sbuf__submit(&buf);
+
+    printf("%s:%-3d: %-25s %-6d [%s]\n",
+           frame->co->src->filename->data,
+           Frame__lineno(frame),
+           pk_opname(byte.op),
+           byte.arg,
+           stack_str->data);
+    c11_string__delete(stack_str);
+}
+
+bool pk_wrapper__self(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    py_assign(py_retval(), argv);
+    return true;
+}
+
+int py_replinput(char* buf, int max_size) {
+    buf[0] = '\0';  // reset first char because we check '@' at the beginning
+
+    int size = 0;
+    bool multiline = false;
+    printf(">>> ");
+
+    while(true) {
+        int c = pk_current_vm->callbacks.getchr();
+        if(c == EOF) return -1;
+
+        if(c == '\n') {
+            char last = '\0';
+            if(size > 0) last = buf[size - 1];
+            if(multiline) {
+                if(last == '\n') {
+                    break;  // 2 consecutive newlines to end multiline input
+                } else {
+                    printf("... ");
+                }
+            } else {
+                if(last == ':' || last == '(' || last == '[' || last == '{' || buf[0] == '@') {
+                    printf("... ");
+                    multiline = true;
+                } else {
+                    break;
+                }
+            }
+        }
+
+        if(size == max_size - 1) {
+            buf[size] = '\0';
+            return size;
+        }
+
+        buf[size++] = c;
+    }
+
+    buf[size] = '\0';
+    return size;
+}
+
+py_Ref py_name2ref(py_Name name) {
+    assert(name != NULL);
+    CachedNames* d = &pk_current_vm->cached_names;
+    py_Ref res = CachedNames__try_get(d, name);
+    if(res != NULL) return res;
+    // not found, create a new one
+    py_StackRef tmp = py_pushtmp();
+    py_newstrv(tmp, py_name2sv(name));
+    CachedNames__set(d, name, tmp);
+    py_pop();
+    return CachedNames__try_get(d, name);
+}
+
+void PyObject__dtor(PyObject* self) {
+    py_Dtor dtor = c11__getitem(TypePointer, &pk_current_vm->types, self->type).dtor;
+    if(dtor) dtor(PyObject__userdata(self));
+    if(self->slots == -1) NameDict__dtor(PyObject__dict(self));
+}
\ No newline at end of file
diff --git a/src/modules/enum.c b/src/modules/enum.c
index f63fa3a1..9c7a5659 100644
--- a/src/modules/enum.c
+++ b/src/modules/enum.c
@@ -86,5 +86,5 @@ void pk__add_module_enum() {
     py_bindproperty(type, "name", Enum__name, NULL);
     py_bindproperty(type, "value", Enum__value, NULL);
 
-    pk__type_info(type)->on_end_subclass = Enum__on_end_subclass;
+    pk_typeinfo(type)->on_end_subclass = Enum__on_end_subclass;
 }
\ No newline at end of file
diff --git a/src/modules/pickle.c b/src/modules/pickle.c
index 3777371c..1c8f92b2 100644
--- a/src/modules/pickle.c
+++ b/src/modules/pickle.c
@@ -61,7 +61,7 @@ static void PickleObject__write_bytes(PickleObject* buf, const void* data, int s
 }
 
 static void c11_sbuf__write_type_path(c11_sbuf* path_buf, py_Type type) {
-    py_TypeInfo* ti = pk__type_info(type);
+    py_TypeInfo* ti = pk_typeinfo(type);
     if(py_isnil(ti->module)) {
         c11_sbuf__write_cstr(path_buf, py_name2str(ti->name));
         return;
@@ -349,7 +349,7 @@ static bool pkl__write_object(PickleObject* buf, py_TValue* obj) {
             // try memo for `is_ptr=true` objects
             if(pkl__try_memo(buf, obj->_obj)) return true;
 
-            py_TypeInfo* ti = pk__type_info(obj->type);
+            py_TypeInfo* ti = pk_typeinfo(obj->type);
             py_Ref f_reduce = py_tpfindmagic(obj->type, __reduce__);
             if(f_reduce != NULL) {
                 if(!py_call(f_reduce, 1, obj)) return false;
diff --git a/src/modules/pkpy.c b/src/modules/pkpy.c
index 397f71d9..58bbc8a6 100644
--- a/src/modules/pkpy.c
+++ b/src/modules/pkpy.c
@@ -60,7 +60,7 @@ static bool pkpy_memory_usage(int argc, py_Ref argv) {
 static bool pkpy_is_user_defined_type(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
     PY_CHECK_ARG_TYPE(0, tp_type);
-    py_TypeInfo* ti = pk__type_info(py_totype(argv));
+    py_TypeInfo* ti = py_touserdata(argv);
     py_newbool(py_retval(), ti->is_python);
     return true;
 }
diff --git a/src/public/cast.c b/src/public/cast.c
index dd1b44bb..4deabef1 100644
--- a/src/public/cast.c
+++ b/src/public/cast.c
@@ -45,49 +45,11 @@ bool py_tobool(py_Ref self) {
 
 py_Type py_totype(py_Ref self) {
     assert(self->type == tp_type);
-    py_Type* ud = py_touserdata(self);
-    return *ud;
+    py_TypeInfo* ud = py_touserdata(self);
+    return ud->index;
 }
 
 void* py_touserdata(py_Ref self) {
     assert(self && self->is_ptr);
     return PyObject__userdata(self->_obj);
 }
-
-bool py_istype(py_Ref self, py_Type type) { return self->type == type; }
-
-bool py_checktype(py_Ref self, py_Type type) {
-    if(self->type == type) return true;
-    return TypeError("expected '%t', got '%t'", type, self->type);
-}
-
-bool py_checkinstance(py_Ref self, py_Type type) {
-    if(py_isinstance(self, type)) return true;
-    return TypeError("expected '%t' or its subclass, got '%t'", type, self->type);
-}
-
-bool py_isinstance(py_Ref obj, py_Type type) { return py_issubclass(obj->type, type); }
-
-bool py_issubclass(py_Type derived, py_Type base) {
-    TypeList* types = &pk_current_vm->types;
-    do {
-        if(derived == base) return true;
-        derived = TypeList__get(types, derived)->base;
-    } while(derived);
-    return false;
-}
-
-py_Type py_typeof(py_Ref self) { return self->type; }
-
-py_Type py_gettype(const char* module, py_Name name) {
-    py_Ref mod;
-    if(module != NULL) {
-        mod = py_getmodule(module);
-        if(!mod) return 0;
-    } else {
-        mod = pk_current_vm->builtins;
-    }
-    py_Ref object = py_getdict(mod, name);
-    if(object && py_istype(object, tp_type)) return py_totype(object);
-    return 0;
-}
\ No newline at end of file
diff --git a/src/public/internal.c b/src/public/internal.c
index 8a9628d5..c7be8853 100644
--- a/src/public/internal.c
+++ b/src/public/internal.c
@@ -238,7 +238,7 @@ bool pk_loadmethod(py_StackRef self, py_Name name) {
                 break;
             case tp_classmethod:
                 self[0] = *py_getslot(cls_var, 0);
-                self[1] = pk__type_info(type)->self;
+                self[1] = pk_typeinfo(type)->self;
                 break;
             default: c11__unreachable();
         }
@@ -247,45 +247,6 @@ bool pk_loadmethod(py_StackRef self, py_Name name) {
     return false;
 }
 
-py_Ref py_tpfindmagic(py_Type t, py_Name name) {
-    // assert(py_ismagicname(name));
-    return py_tpfindname(t, name);
-}
-
-py_Ref py_tpfindname(py_Type t, py_Name name) {
-    py_TypeInfo* ti = pk__type_info(t);
-    do {
-        py_Ref res = py_getdict(&ti->self, name);
-        if(res) return res;
-        ti = ti->base_ti;
-    } while(ti);
-    return NULL;
-}
-
-py_Type py_tpbase(py_Type t) {
-    assert(t);
-    py_TypeInfo* ti = pk__type_info(t);
-    return ti->base;
-}
-
-PK_DEPRECATED py_Ref py_tpgetmagic(py_Type type, py_Name name) {
-    // assert(py_ismagicname(name));
-    py_TypeInfo* ti = pk__type_info(type);
-    py_Ref retval = py_getdict(&ti->self, name);
-    return retval != NULL ? retval : py_NIL();
-}
-
-py_Ref py_tpobject(py_Type type) {
-    assert(type);
-    return &pk__type_info(type)->self;
-}
-
-const char* py_tpname(py_Type type) {
-    if(!type) return "nil";
-    py_Name name = pk__type_info(type)->name;
-    return py_name2str(name);
-}
-
 bool py_tpcall(py_Type type, int argc, py_Ref argv) {
     return py_call(py_tpobject(type), argc, argv);
 }
diff --git a/src/public/modules.c b/src/public/modules.c
index a1d0d98d..8ffa0348 100644
--- a/src/public/modules.c
+++ b/src/public/modules.c
@@ -843,7 +843,7 @@ static bool super__new__(int argc, py_Ref argv) {
             if(callable->type == tp_function) {
                 Function* func = py_touserdata(callable);
                 if(func->clazz != NULL) {
-                    class_arg = *(py_Type*)PyObject__userdata(func->clazz);
+                    class_arg = ((py_TypeInfo*)PyObject__userdata(func->clazz))->index;
                     if(frame->co->nlocals > 0) { self_arg = &frame->locals[0]; }
                 }
             }
@@ -851,7 +851,7 @@ static bool super__new__(int argc, py_Ref argv) {
         if(class_arg == 0 || self_arg == NULL) return RuntimeError("super(): no arguments");
         if(self_arg->type == tp_type) {
             // f(cls, ...)
-            class_arg = pk__type_info(class_arg)->base;
+            class_arg = pk_typeinfo(class_arg)->base;
             if(class_arg == 0) return RuntimeError("super(): base class is invalid");
             py_assign(py_retval(), py_tpobject(class_arg));
             return true;
@@ -868,7 +868,7 @@ static bool super__new__(int argc, py_Ref argv) {
         return TypeError("super() takes 0 or 2 arguments");
     }
 
-    class_arg = pk__type_info(class_arg)->base;
+    class_arg = pk_typeinfo(class_arg)->base;
     if(class_arg == 0) return RuntimeError("super(): base class is invalid");
 
     py_Type* p_class_arg = py_newobject(py_retval(), tp_super, 1, sizeof(py_Type));
diff --git a/src/public/py_object.c b/src/public/py_object.c
index c056642e..6ed83760 100644
--- a/src/public/py_object.c
+++ b/src/public/py_object.c
@@ -4,8 +4,8 @@
 
 bool pk__object_new(int argc, py_Ref argv) {
     if(argc == 0) return TypeError("object.__new__(): not enough arguments");
-    py_Type cls = py_totype(py_arg(0));
-    py_TypeInfo* ti = pk__type_info(cls);
+    py_TypeInfo* ti = py_touserdata(argv);
+    py_Type cls = ti->index;
     if(!ti->is_python) {
         return TypeError("object.__new__(%t) is not safe, use %t.__new__() instead", cls, cls);
     }
@@ -72,7 +72,7 @@ static bool type__new__(int argc, py_Ref argv) {
 
 static bool type__base__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
-    py_TypeInfo* ti = pk__type_info(py_totype(argv));
+    py_TypeInfo* ti = py_touserdata(argv);
     if(ti->base) {
         py_assign(py_retval(), &ti->base_ti->self);
     } else {
@@ -83,7 +83,7 @@ static bool type__base__(int argc, py_Ref argv) {
 
 static bool type__name__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
-    py_TypeInfo* ti = pk__type_info(py_totype(argv));
+    py_TypeInfo* ti = py_touserdata(argv);
     py_assign(py_retval(), py_name2ref(ti->name));
     return true;
 }
@@ -100,7 +100,7 @@ static bool type__or__(int argc, py_Ref argv) {
 
 static bool type__module__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
-    py_TypeInfo* ti = pk__type_info(py_totype(argv));
+    py_TypeInfo* ti = py_touserdata(argv);
     if(py_isnil(ti->module)) {
         py_newnone(py_retval());
     } else {
@@ -112,7 +112,7 @@ static bool type__module__(int argc, py_Ref argv) {
 
 static bool type__annotations__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
-    py_TypeInfo* ti = pk__type_info(py_totype(argv));
+    py_TypeInfo* ti = py_touserdata(argv);
     if(py_isnil(&ti->annotations)) {
         py_newdict(py_retval());
     } else {
diff --git a/src/public/py_ops.c b/src/public/py_ops.c
index ed643c86..a6a60214 100644
--- a/src/public/py_ops.c
+++ b/src/public/py_ops.c
@@ -52,7 +52,7 @@ int py_bool(py_Ref val) {
 }
 
 bool py_hash(py_Ref val, int64_t* out) {
-    py_TypeInfo* ti = pk__type_info(val->type);
+    py_TypeInfo* ti = pk_typeinfo(val->type);
     do {
         py_Ref slot_hash = py_getdict(&ti->self, __hash__);
         if(slot_hash && py_isnone(slot_hash)) break;
@@ -93,8 +93,8 @@ int py_next(py_Ref val) {
 
 bool py_getattr(py_Ref self, py_Name name) {
     // https://docs.python.org/3/howto/descriptor.html#invocation-from-an-instance
-    py_Type type = self->type;
-    py_Ref cls_var = py_tpfindname(type, name);
+    py_TypeInfo* ti = pk_typeinfo(self->type);
+    py_Ref cls_var = pk_tpfindname(ti, name);
     if(cls_var) {
         // handle descriptor
         if(py_istype(cls_var, tp_property)) {
@@ -111,8 +111,9 @@ bool py_getattr(py_Ref self, py_Name name) {
                 return true;
             }
         } else {
-            py_Type* inner_type = py_touserdata(self);
-            py_Ref res = py_tpfindname(*inner_type, name);
+            // self is a type object
+            py_TypeInfo* inner_type = py_touserdata(self);
+            py_Ref res = pk_tpfindname(inner_type, name);
             if(res) {
                 if(py_istype(res, tp_staticmethod)) {
                     res = py_getslot(res, 0);
@@ -145,7 +146,7 @@ bool py_getattr(py_Ref self, py_Name name) {
                 return true;
             }
             case tp_classmethod: {
-                py_newboundmethod(py_retval(), py_tpobject(type), py_getslot(cls_var, 0));
+                py_newboundmethod(py_retval(), &ti->self, py_getslot(cls_var, 0));
                 return true;
             }
             default: {
@@ -156,7 +157,7 @@ bool py_getattr(py_Ref self, py_Name name) {
         }
     }
 
-    py_Ref fallback = py_tpfindmagic(type, __getattr__);
+    py_Ref fallback = pk_tpfindmagic(ti, __getattr__);
     if(fallback) {
         py_push(fallback);
         py_push(self);
diff --git a/src/public/typecast.c b/src/public/typecast.c
new file mode 100644
index 00000000..a00fd491
--- /dev/null
+++ b/src/public/typecast.c
@@ -0,0 +1,45 @@
+#include "pocketpy/objects/base.h"
+#include "pocketpy/pocketpy.h"
+
+#include "pocketpy/objects/object.h"
+#include "pocketpy/interpreter/vm.h"
+
+bool py_istype(py_Ref self, py_Type type) { return self->type == type; }
+
+bool py_checktype(py_Ref self, py_Type type) {
+    if(self->type == type) return true;
+    return TypeError("expected '%t', got '%t'", type, self->type);
+}
+
+bool py_checkinstance(py_Ref self, py_Type type) {
+    if(py_isinstance(self, type)) return true;
+    return TypeError("expected '%t' or its subclass, got '%t'", type, self->type);
+}
+
+bool py_isinstance(py_Ref obj, py_Type type) { return py_issubclass(obj->type, type); }
+
+bool py_issubclass(py_Type derived, py_Type base) {
+    assert(derived != 0 && base != 0);
+    py_TypeInfo* derived_ti = pk_typeinfo(derived);
+    py_TypeInfo* base_ti = pk_typeinfo(base);
+    do {
+        if(derived_ti == base_ti) return true;
+        derived_ti = derived_ti->base_ti;
+    } while(derived_ti);
+    return false;
+}
+
+py_Type py_typeof(py_Ref self) { return self->type; }
+
+py_Type py_gettype(const char* module, py_Name name) {
+    py_Ref mod;
+    if(module != NULL) {
+        mod = py_getmodule(module);
+        if(!mod) return tp_nil;
+    } else {
+        mod = pk_current_vm->builtins;
+    }
+    py_Ref object = py_getdict(mod, name);
+    if(object && py_istype(object, tp_type)) return py_totype(object);
+    return tp_nil;
+}
\ No newline at end of file