fix: sanitizer checks fix (iteration 3 - final)

- Add token check before parsing statement or program
- Fix program freeing

.gdbinit

@@ -2,4 +2,14 @@ skip peek
 skip consume
 skip next
 skip is
+skip -rfunction fzl_mk*
+skip -rfunction fzl_free*
+skip -rfunction fzl_symt*
+skip add_const
+skip push_op
+skip push_word
+skip -rfunction fzl_env*
+skip tok_to_type
+skip nest_ctx
+skip fin_ctx
 

CMakeLists.txt

@@ -1,8 +1,14 @@
-cmake_minimum_required(VERSION 4.3)
+cmake_minimum_required(VERSION 3.16)
 project(fz-lang
 	LANGUAGES C)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+add_compile_options(-Wall -Wextra -Werror=implicit-function-declaration)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+	add_compile_options(-fsanitize=address,undefined -g)
+	add_link_options(-fsanitize=address,undefined)
+endif()
 
 include_directories(include)
 
@@ -18,6 +24,7 @@ add_executable(fzc
 	src/compiler/utils/fzl_symtable.c
 	src/compiler/utils/fzl_linked.c
 	src/compiler/utils/fzl_options.c
+	src/compiler/utils/fzl_ctable.c
 	src/compiler/main.c)
 
 # Virtual machine
@@ -65,6 +72,22 @@ add_test(
 	NAME compile_comment
 	COMMAND fzc -o "${CMAKE_CURRENT_BINARY_DIR}/comment.fzb" "${CMAKE_CURRENT_SOURCE_DIR}/exl/comment.fzs"
 )
+add_test(
+	NAME compile_class
+	COMMAND fzc -o "${CMAKE_CURRENT_BINARY_DIR}/class.fzb" "${CMAKE_CURRENT_SOURCE_DIR}/exl/class.fzs"
+)
+add_test(
+	NAME compile_raii
+	COMMAND fzc -o "${CMAKE_CURRENT_BINARY_DIR}/raii.fzb" "${CMAKE_CURRENT_SOURCE_DIR}/exl/raii.fzs"
+)
+add_test(
+	NAME compile_borrow
+	COMMAND fzc -o "${CMAKE_CURRENT_BINARY_DIR}/borrow.fzb" "${CMAKE_CURRENT_SOURCE_DIR}/exl/borrow.fzs"
+)
+add_test(
+	NAME compile_hard_1
+	COMMAND fzc -o "${CMAKE_CURRENT_BINARY_DIR}/hard-1.fzb" "${CMAKE_CURRENT_SOURCE_DIR}/exl/hard-1.fzs"
+)
 
 set_tests_properties(compile_problematic_hw PROPERTIES WILL_FAIL TRUE)
 
@@ -100,4 +123,20 @@ add_test(
 	NAME runtime_comment
 	COMMAND fz "${CMAKE_CURRENT_BINARY_DIR}/comment.fzb"
 )
+add_test(
+	NAME runtime_class
+	COMMAND fz "${CMAKE_CURRENT_BINARY_DIR}/class.fzb"
+)
+add_test(
+	NAME runtime_raii
+	COMMAND fz "${CMAKE_CURRENT_BINARY_DIR}/raii.fzb"
+)
+add_test(
+	NAME runtime_borrow
+	COMMAND fz "${CMAKE_CURRENT_BINARY_DIR}/borrow.fzb"
+)
+add_test(
+	NAME runtime_hard_1
+	COMMAND fz "${CMAKE_CURRENT_BINARY_DIR}/hard-1.fzb"
+)
 

README.md

@@ -18,6 +18,8 @@ At the moment, the language has the following capabilities:
   - `str` - strings
   - `bool` - boolean
 - Assignments
+- Functions
+- Classes and objects
 
 Working examples of code can be found in `exl/` directory.
 
@@ -51,8 +53,9 @@ This file provides set up codestyle rules.
 There is two targets in Makefile for debugging purposes: `build-c` for the compiler and `build-vm` for the VM.
 Each target can be called with `FILE` variable. For example:
 
-
 ```shell
 $ make debug-c FILE=exl/hw.fzs
 ```
 
+To test new features, use `test` make target and the tests, defined in `CMakeLists.txt`.
+

README.ru.md

@@ -9,7 +9,7 @@
 На данный момент язык имеет:
 
 - Встроенную функцию `printline` для вывода аргумента в stdout
-- Строковый и числовой литералы
+- Строковый, булев и числовой литералы
 - Арифметические операции: сложение, вычитание, умножение, деление, модуло, возведение в степень
 - Декларация переменных со следующими типами:
   - `uint`, `int` - целые числа размером с машинное слово
@@ -18,6 +18,8 @@
   - `str` - строки
   - `bool` - булевы
 - Присваивание
+- Функции
+- Классы и объекты
 
 Примеры кода лежат в директории `exl/`.
 
@@ -55,3 +57,5 @@
 $ make debug-c FILE=exl/hw.fzs
 ```
 
+Для проверки новых фич, нужно использовать make-таргет `test`, а тесты писать в `CMakeLists.txt`.
+

exl/borrow.fzs

@@ -0,0 +1,46 @@
+class A
+{
+  uint some;
+}
+
+fn doSome(A a) A
+{
+  // NOTE: section below won't change `a.some` value
+
+  if (a.some < 1)
+  {
+    a.some = 1;
+    return a;
+  }
+
+  return a;
+}
+
+fn doSomeNew() A
+{
+  if (1 == 1)
+  {
+    return new A;
+  }
+}
+
+A a = new A;
+a.some = 0;
+if (a.some != 0)
+{
+  printline("Test failed (first a.some != 0)");
+  exit(1);
+}
+else printline(a);
+
+a = doSome(a);
+if (a.some != 1)
+{
+  printline("Test failed (2nd a.some != 1)");
+  exit(1);
+}
+else printline(a);
+
+A b = doSomeNew();
+printline(b);
+

exl/class.fzs

@@ -0,0 +1,36 @@
+class Point
+{
+  int x;
+  int y;
+
+  // Move point by [dx,dy]
+  fn move(int dx, int dy) {
+    this.x = this.x + dx;
+    this.y = this.y + dy;
+  }
+}
+
+Point obj = new Point;
+obj.x = 1;
+obj.y = 2;
+
+printline("Current X,Y:");
+printline(obj.x);
+printline(obj.y);
+
+// NOTE: WHY THE FUCK THIS FUCKING COMPILER REQUIRES ';' AFTER '='?!
+//      |
+//      v
+obj.move(9, 8);
+printline("X,Y after move:");
+printline(obj.x);
+printline(obj.y);
+
+if (obj.x == 10 && obj.y == 10)
+  printline("Test passed");
+else
+{
+  printline("Test failed");
+  exit(1);
+}
+

exl/conditions.fzs

@@ -1,13 +1,17 @@
 bool flag = true;
 
 if (!flag)
+{
   printline("buhhh, flag is not true");
+  exit(1);
+}
 else if (2 + 2 >= 4)
 {
   printline ("two plus two is four");
 }
 else {
   printline("gotcha");
+  exit(1);
 }
 
 {

exl/fn.fzs

@@ -1,4 +1,4 @@
-int fib(int n)
+fn fib(int n) int
 {
   if (n <= 1)
     return n;
@@ -6,7 +6,7 @@ int fib(int n)
   return fib(n - 1) + fib(n - 2);
 }
 
-uint sum(uint a, uint b)
+fn sum(uint a, uint b) uint
 {
   return a + b;
 }
@@ -15,10 +15,18 @@ printline("Test #1: fibonacci");
 int result = fib(7);
 if (result == 13)
   printline("Recurse test passed");
-else printline("Recurse test failed");
+else
+{
+  printline("Recurse test failed");
+  exit(1);
+}
 
 printline("Test #2: sum");
 if (sum(2, 2) == 4)
   printline("Sum test passed");
-else printline("Sum test failed");
+else
+{
+  printline("Sum test failed");
+  exit(1);
+}
 

exl/hard-1.fzs

@@ -0,0 +1,66 @@
+class Node
+{
+  int value;
+  Node next;
+
+  fn append(int val) Node
+  {
+    if (this.next == null)
+    {
+      Node tail = new Node;
+      tail.value = val;
+      tail.next = null;
+      this.next = tail;
+      return this;
+    }
+
+    this.next = this.next.append(val);
+    return this;
+  }
+
+  fn sum() int
+  {
+    if (this.next == null)
+      return this.value;
+
+    return this.value + this.next.sum();
+  }
+
+  fn printList()
+  {
+    printline(this.value);
+    if (this.next != null)
+      this.next.printList();
+  }
+}
+
+fn createList(int count) Node
+{
+  if (count <= 0)
+    return null;
+
+  Node head = new Node;
+  head.value = count;
+  head.next = createList(count - 1);
+  return head;
+}
+
+printline("===== Test 1: factory & recursive escaping =====");
+Node list = createList(3);
+printline("Elements:");
+list.printList();
+
+printline("===== Test 2: mutation & methods =====");
+list = list.append(10);
+int total = list.sum();
+printline("Sum of elements:");
+printline(total);
+
+if (total == 16)
+  printline("Tests passed!");
+else
+{
+  printline("Tests failed");
+  exit(1);
+}
+

exl/raii.fzs

@@ -0,0 +1,46 @@
+class Animal
+{
+  str type;
+  str name;
+  int age;
+
+  fn copy() Animal
+  {
+    Animal cp = new Animal;
+    cp.type = this.type;
+    cp.name = this.name;
+    cp.age = this.age;
+
+    return cp;
+  }
+}
+
+Animal a = new Animal;
+a.type = "Cow";
+a.name = "Buryatka";
+a.age = 5;
+
+Animal b = a.copy();
+b.name = "Gavryusha";
+b.age = 10;
+
+printline(a);
+printline(b);
+
+printline("Types are same:");
+printline(a.type == b.type);
+
+printline("Names are NOT the same");
+printline(a.name != b.name);
+
+printline("1st age less than 2nd");
+printline(a.age < b.age);
+
+if (a.type == b.type && a.name != b.name && a.age < b.age)
+  printline("Test passed");
+else
+{
+  printline("Test failed");
+  exit(1);
+}
+

include/common/fzl_builtins.h

@@ -3,7 +3,8 @@
 
 typedef enum
 {
-  FZL_BUILTIN_PRINTLINE // Print message in arg with newline at end
+  FZL_BUILTIN_PRINTLINE, // Print message in arg with newline at end
+  FZL_BUILTIN_EXIT,      // Exit program with code specified in arg
 } fzl_builtin_t;
 
 #endif // FZL_BUILTINS_H

include/common/fzl_opcodes.h

@@ -21,6 +21,12 @@ typedef enum
   FZL_OPCODE_CALL = 0xF30001, // Call function
   FZL_OPCODE_RET  = 0xF30002, // Return from function
 
+  FZL_OPCODE_ALLOC_OBJECT  = 0xFA0001, // Allocate N slots
+  FZL_OPCODE_GET_FIELD     = 0xFA0002, // Get field N of an object at dstack
+  FZL_OPCODE_SET_FIELD     = 0xFA0003, // Set field N of an object at dstack
+  FZL_OPCODE_ESCAPE_OBJECT = 0xFA0004, // Make parent envtable as owner
+  FZL_OPCODE_DEREFERENCE   = 0xFA0005, // Dereference address
+
   FZL_OPCODE_ADD = 0xA00001, // Sum two numbers in dstack
   FZL_OPCODE_SUB = 0xA00002, // Subract two numbers in dstack
   FZL_OPCODE_MUL = 0xA00003, // Multiply two numbers in dstack
@@ -36,6 +42,12 @@ typedef enum
   FZL_OPCODE_CMP_GT   = 0xB00005, // Greater than
   FZL_OPCODE_CMP_GTEQ = 0xB00006, // Greater than or equal
 
+  FZL_OPCODE_CMP_EQ_STR  = 0xB10001, // Strings equality
+  FZL_OPCODE_CMP_NEQ_STR = 0xB10002, // Strings non-equality
+
+  FZL_OPCODE_CMP_EQ_OBJ  = 0xB20001, // Objects equality (by pointer)
+  FZL_OPCODE_CMP_NEQ_OBJ = 0xB20002, // Objects non-equality (by pointer)
+
   FZL_OPCODE_AND = 0xC00001, // A && B
   FZL_OPCODE_OR  = 0xC00002, // A || B
 

include/common/fzl_types.h

@@ -4,6 +4,7 @@
 typedef enum
 {
   FZL_TYPE_NULL,
+  FZL_TYPE_OBJECT,
 
   FZL_TYPE_STRING,
   FZL_TYPE_CHAR,

include/common/fzl_value.h

@@ -13,6 +13,8 @@ typedef struct
 
   union
   {
+    void *obj;
+
     struct
     {
       const char *value;

include/compiler/fzl_parser.h

@@ -1,7 +1,6 @@
 #ifndef FZL_PARSER_H
 #define FZL_PARSER_H
 
-#include "common/fzl_types.h"
 #include <compiler/fzl_reader.h>
 #include <compiler/fzl_token.h>
 #include <stddef.h>
@@ -16,6 +15,9 @@ typedef enum
   FZL_NODETYPE_CONDITIONAL,
   FZL_NODETYPE_FUNCTION,
   FZL_NODETYPE_RETURN,
+  FZL_NODETYPE_CLASS,
+  FZL_NODETYPE_FIELD,
+  FZL_NODETYPE_CONSTRUCT,
 
   FZL_NODETYPE_ADD,
   FZL_NODETYPE_SUB,
@@ -113,6 +115,31 @@ typedef struct fzl_node
     {
       struct fzl_node *value;
     } ret;
+
+    // Class declaration
+    struct
+    {
+      fzl_token_t *name;
+
+      struct fzl_node **fields;
+      size_t fields_count;
+
+      struct fzl_node **methods;
+      size_t methods_count;
+    } class;
+
+    // Member access
+    struct
+    {
+      struct fzl_node *parent;
+      struct fzl_node *field;
+    } memb;
+
+    // Object construct
+    struct
+    {
+      struct fzl_node *name;
+    } construct;
   };
 } fzl_node_t;
 

include/compiler/fzl_token.h

@@ -8,6 +8,10 @@
 // Token type
 typedef enum
 {
+  FZL_TOKTYPE_CLASS, // class
+  FZL_TOKTYPE_NEW,   // new
+
+  FZL_TOKTYPE_FUNCTION, // fn
   FZL_TOKTYPE_RETURN,   // return
 
   FZL_TOKTYPE_IF,   // if
@@ -30,6 +34,7 @@ typedef enum
   FZL_TOKTYPE_STR_LITERAL,  // ""
   FZL_TOKTYPE_NUM_LITERAL,  // 123
   FZL_TOKTYPE_BOOL_LITERAL, // true
+  FZL_TOKTYPE_NULL_LITERAL, // null
 
   FZL_TOKTYPE_DAMPERSAND, // &&
   FZL_TOKTYPE_DVBAR,      // ||

include/compiler/fzl_walker.h

@@ -5,10 +5,20 @@
 #include <common/fzl_types.h>
 #include <compiler/fzl_parser.h>
 #include <compiler/utils/fzl_const_pool.h>
+#include <compiler/utils/fzl_ctable.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
 
+// Type of context
+typedef enum
+{
+  FZL_WALK_CTX_TYPE_GLOBAL,
+  FZL_WALK_CTX_TYPE_FN,
+  FZL_WALK_CTX_TYPE_CLASS,
+  FZL_WALK_CTX_TYPE_ASSIGN
+} fzl_walk_ctx_type_t;
+
 // Internal walk function result
 typedef struct
 {
@@ -16,11 +26,16 @@ typedef struct
 
   char *error_msg;
   bool error;
+
+  char *classname;
 } fzl_walk_res_t;
 
 // Function context descriptor
-typedef struct
+typedef struct fzl_walk_ctx
 {
+  fzl_walk_ctx_type_t type;
+  struct fzl_walk_ctx *parent;
+
   fzl_node_t *fn;
   size_t initial_env_lvl;
 } fzl_walk_ctx_t;
@@ -39,6 +54,9 @@ typedef struct
   size_t sym_top;
 
   fzl_walk_ctx_t *ctx;
+
+  fzl_ctable_t *classes[64];
+  size_t classes_count;
 } fzl_walker_t;
 
 // Allocate new walker

include/compiler/utils/fzl_const_pool.h

@@ -4,12 +4,12 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 
 // Constant types
 typedef enum
 {
   FZL_CONSTTYPE_STRING,
-  FZL_CONSTTYPE_NUMBER
 } fzl_consttype_t;
 
 // Constant descriptor
@@ -34,7 +34,7 @@ typedef struct
 
 typedef struct
 {
-  size_t pool_index;
+  ssize_t pool_index;
 } fzl_const_hash_slot_t;
 
 // Constant pool descriptor
@@ -53,13 +53,13 @@ typedef struct
 bool fzl_consts_equal(fzl_const_t a, fzl_const_t b);
 
 // Get hash of specified constant
-static uint32_t fzl_hash_const(fzl_const_t c);
+uint32_t fzl_hash_const(fzl_const_t c);
 
 // Allocate constants hash pool
 fzl_const_hash_pool_t *fzl_mkconstpool();
 
 // Resize the hash table
-static void fzl_consts_pool_resize_hash(fzl_const_hash_pool_t *pool);
+void fzl_consts_pool_resize_hash(fzl_const_hash_pool_t *pool);
 
 // Push constant. Returns unique index
 size_t fzl_consts_pool_add(fzl_const_hash_pool_t *pool, fzl_const_t c);

include/compiler/utils/fzl_ctable.h

@@ -0,0 +1,30 @@
+#ifndef FZL_CTABLE_H
+#define FZL_CTABLE_H
+
+#include <common/fzl_types.h>
+#include <stddef.h>
+
+// Class field descriptor
+typedef struct
+{
+  char *name;
+  size_t slot_index;
+  fzl_type_t type;
+} fzl_ctable_field_t;
+
+// Class table descriptor
+typedef struct
+{
+  char *name;
+  fzl_ctable_field_t *fields;
+  size_t fields_count;
+  size_t fields_remainder;
+} fzl_ctable_t;
+
+// Allocate class table
+fzl_ctable_t *fzl_mkctable(char *name);
+
+// Free class table
+void fzl_freectable(fzl_ctable_t *ct);
+
+#endif // FZL_CTABLE_H

include/compiler/utils/fzl_symtable.h

@@ -10,7 +10,8 @@ typedef enum
 {
   FZL_SYMTABLE_RESULT_OK,
   FZL_SYMTABLE_RESULT_ERR,
-  FZL_SYMTABLE_RESULT_EXISTS
+  FZL_SYMTABLE_RESULT_EXISTS,
+  FZL_SYMTABLE_RESULT_NOT_OBJECT
 } fzl_symtable_res_t;
 
 // Symbols table entry descriptor
@@ -19,6 +20,8 @@ typedef struct
   char *name;
   fzl_type_t type;
   size_t ip;
+
+  char *classname;
 } fzl_sym_t;
 
 // Symbols table descriptor
@@ -37,6 +40,10 @@ fzl_symtable_t *fzl_mksymt();
 fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, char *name,
                                 fzl_type_t type, uint64_t ip);
 
+// Assign class name to object type
+fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
+                                        char *classname);
+
 // Get entry from specified symtable
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res);
 

include/vm/fzl_vm.h

@@ -6,6 +6,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <vm/fzl_vm_env.h>
+#include <vm/fzl_vm_object.h>
 
 // VM descriptor
 typedef struct

include/vm/fzl_vm_env.h

@@ -4,6 +4,7 @@
 #include <common/fzl_value.h>
 #include <stdbool.h>
 #include <stddef.h>
+#include <vm/fzl_vm_object.h>
 
 typedef enum
 {
@@ -27,6 +28,10 @@ typedef struct
   size_t remainder;
 
   fzl_vm_env_entry_t *table;
+
+  fzl_vm_object_t **owned_objects;
+  size_t owned_objects_remainder;
+  size_t owned_objects_count;
 } fzl_vm_env_t;
 
 // Allocate env table

include/vm/fzl_vm_object.h

@@ -0,0 +1,14 @@
+#ifndef FZL_VM_OBJECT_H
+#define FZL_VM_OBJECT_H
+
+#include <common/fzl_value.h>
+#include <stddef.h>
+
+// Object descriptor
+typedef struct
+{
+  fzl_value_t *values;
+  size_t values_count;
+} fzl_vm_object_t;
+
+#endif // FZL_VM_OBJECT_H

src/compiler/fzl_debug.c

@@ -27,11 +27,31 @@ void print_node(fzl_node_t *node, int level)
   if (!node)
     return;
 
-  size_t lvllen = print_level(levelbuf, level);
   strcpy(printbuf, levelbuf);
 
   switch (node->type)
   {
+    case FZL_NODETYPE_CONSTRUCT:
+      printf("%s Construct class '%s':\n", levelbuf,
+             (char *)node->construct.name->token->value);
+      break;
+
+    case FZL_NODETYPE_CLASS:
+      printf("%s Class '%s':\n", levelbuf, (char *)node->token->value);
+      printf("-%s Fields:\n", levelbuf);
+      for (size_t i = 0; i < node->class.fields_count; i++)
+        print_node(node->class.fields[i], level + 2);
+      printf("-%s Methods:\n", levelbuf);
+      for (size_t i = 0; i < node->class.methods_count; i++)
+        print_node(node->class.methods[i], level + 2);
+      break;
+
+    case FZL_NODETYPE_FIELD:
+      printf("%s Field '%s' access:\n", levelbuf,
+             (char *)node->memb.field->token->value);
+      print_node(node->memb.parent, level + 1);
+      break;
+
     case FZL_NODETYPE_DECLARATION:
       printf("%s Declare variable with type %d:\n", levelbuf,
              node->var.type->type);
@@ -112,6 +132,8 @@ void print_node(fzl_node_t *node, int level)
         print_node(node->ret.value, level + 1);
       break;
 
+    case FZL_NODETYPE_AND:
+    case FZL_NODETYPE_OR:
     case FZL_NODETYPE_EQUAL:
     case FZL_NODETYPE_NEQUAL:
     case FZL_NODETYPE_LESS:

src/compiler/fzl_parser.c

@@ -9,6 +9,24 @@
 char plast_err[256];
 fzl_token_t *last_known_tok = NULL;
 
+fzl_token_t null_tok = {
+    .type        = FZL_TOKTYPE_TYPE,
+    .filename    = "",
+    .ln          = 0,
+    .cn          = 0,
+    .store_value = false,
+    .value       = "null",
+    .value_sz    = 4,
+};
+
+fzl_token_t this_tok = {.type        = FZL_TOKTYPE_NAME,
+                        .filename    = "",
+                        .ln          = 0,
+                        .cn          = 0,
+                        .store_value = false,
+                        .value       = "this",
+                        .value_sz    = 4};
+
 fzl_parser_t *fzl_mkparser(fzl_reader_ll_t *first)
 {
   if (!first)
@@ -35,6 +53,7 @@ fzl_parser_t *fzl_mkparser(fzl_reader_ll_t *first)
 fzl_node_t *fzl_mknode(fzl_nodetype_t type, fzl_token_t *token)
 {
   fzl_node_t *node = malloc(sizeof(fzl_node_t));
+  memset(node, 0, sizeof(fzl_node_t));
 
   if (!node)
     return NULL;
@@ -56,24 +75,12 @@ static fzl_token_t *peek(fzl_parser_t *parser)
   return parser->cursor->token;
 }
 
-// Get token at (cursor + 1)
-static fzl_token_t *next(fzl_parser_t *parser)
-{
-  if (!parser || !parser->cursor)
-    return NULL;
-
-  fzl_reader_ll_t *next = parser->cursor->next;
-  if (!next)
-    return NULL;
-
-  return next->token;
-}
-
 // Consume token at cursor and move to the next
 static fzl_token_t *consume(fzl_parser_t *parser)
 {
-  if (!parser || !parser->cursor)
+  if (!parser || !parser->cursor || !parser->cursor->token)
     return NULL;
+
   fzl_token_t *tok = parser->cursor->token;
   parser->cursor   = parser->cursor->next;
   return tok;
@@ -139,17 +146,10 @@ fzl_node_t *parse_primary(fzl_parser_t *parser)
   if (!parser || !peek(parser))
     return NULL;
 
-  if (is(parser, FZL_TOKTYPE_STR_LITERAL))
+  if (is(parser, FZL_TOKTYPE_STR_LITERAL) ||
-  {
+      is(parser, FZL_TOKTYPE_NUM_LITERAL) ||
-    fzl_token_t *tok = consume(parser);
+      is(parser, FZL_TOKTYPE_BOOL_LITERAL) ||
-    return fzl_mknode(FZL_NODETYPE_LITERAL, tok);
+      is(parser, FZL_TOKTYPE_NULL_LITERAL))
-  }
-  else if (is(parser, FZL_TOKTYPE_NUM_LITERAL))
-  {
-    fzl_token_t *tok = consume(parser);
-    return fzl_mknode(FZL_NODETYPE_LITERAL, tok);
-  }
-  else if (is(parser, FZL_TOKTYPE_BOOL_LITERAL))
   {
     fzl_token_t *tok = consume(parser);
     return fzl_mknode(FZL_NODETYPE_LITERAL, tok);
@@ -170,7 +170,14 @@ fzl_node_t *parse_primary(fzl_parser_t *parser)
   else if (is(parser, FZL_TOKTYPE_NAME))
   {
     fzl_token_t *name = consume(parser);
+    if (!is(parser, FZL_TOKTYPE_NAME))
       return fzl_mknode(FZL_NODETYPE_IDENTIFIER, name);
+
+    fzl_token_t *realname = consume(parser); // :D
+    fzl_node_t *decl      = fzl_mknode(FZL_NODETYPE_DECLARATION, name);
+    decl->var.type        = name;
+    decl->var.identifier  = fzl_mknode(FZL_NODETYPE_IDENTIFIER, realname);
+    return decl;
   }
   else if (is(parser, FZL_TOKTYPE_TYPE))
   {
@@ -204,7 +211,6 @@ fzl_node_t *parse_postfix(fzl_parser_t *parser)
     return NULL;
 
   fzl_node_t *left = parse_primary(parser);
-  fzl_node_t *right = NULL;
 
   if (!left)
   {
@@ -215,10 +221,14 @@ fzl_node_t *parse_postfix(fzl_parser_t *parser)
     return NULL;
   }
 
-  while (is(parser, FZL_TOKTYPE_LPAREN))
+  if (is(parser, FZL_TOKTYPE_LPAREN) || is(parser, FZL_TOKTYPE_DOT))
   {
-    consume(parser);
+    while (is(parser, FZL_TOKTYPE_LPAREN) || is(parser, FZL_TOKTYPE_DOT))
+    {
+      fzl_token_t *post = consume(parser);
 
+      if (post->type == FZL_TOKTYPE_LPAREN)
+      {
         size_t args_capacity = 2;
         size_t args_count    = 0;
         fzl_node_t **args    = malloc(args_capacity * sizeof(fzl_node_t *));
@@ -235,7 +245,7 @@ fzl_node_t *parse_postfix(fzl_parser_t *parser)
           if (args_capacity <= args_count)
           {
             args_capacity *= 2;
-        args = realloc(args, args_capacity * sizeof(fzl_node_t));
+            args = realloc(args, args_capacity * sizeof(fzl_node_t *));
           }
 
           args[args_count] = arg;
@@ -262,6 +272,26 @@ fzl_node_t *parse_postfix(fzl_parser_t *parser)
 
         left = node;
       }
+      else if (post->type == FZL_TOKTYPE_DOT)
+      {
+        if (!is(parser, FZL_TOKTYPE_NAME))
+        {
+          snprintf(plast_err, sizeof(plast_err),
+                   "'%s': expected name after '.' at %ld:%ld",
+                   last_known_tok->filename, last_known_tok->ln,
+                   last_known_tok->cn);
+          return NULL;
+        }
+
+        fzl_token_t *name = consume(parser);
+        fzl_node_t *node  = fzl_mknode(FZL_NODETYPE_FIELD, name);
+        node->memb.parent = left;
+        node->memb.field  = fzl_mknode(FZL_NODETYPE_IDENTIFIER, name);
+
+        left = node;
+      }
+    }
+  }
 
   return left;
 }
@@ -540,38 +570,238 @@ fzl_node_t *parse_or(fzl_parser_t *parser)
   return left;
 }
 
-// Expression parsing
+// Object construct parsing
-fzl_node_t *parse_expression(fzl_parser_t *parser) { return parse_and(parser); }
+fzl_node_t *parse_new(fzl_parser_t *parser)
-
-// Statement parsing
-fzl_node_t *parse_statement(fzl_parser_t *parser)
 {
-  fzl_node_t *res = NULL;
+  if (!is(parser, FZL_TOKTYPE_NEW))
+    return parse_or(parser);
 
-  if (is(parser, FZL_TOKTYPE_TYPE))
+  fzl_token_t *new    = consume(parser);
-  {
+  fzl_node_t *objname = parse_or(parser);
-    fzl_token_t *type = peek(parser);
+  if (objname->type != FZL_NODETYPE_IDENTIFIER &&
-    if (type->type == FZL_TOKTYPE_TYPE)
+      objname->type != FZL_NODETYPE_FIELD)
-      consume(parser);
-
-    if (type->type == FZL_TOKTYPE_TYPE &&
-        next(parser)->type == FZL_TOKTYPE_LPAREN)
-    {
-      fzl_token_t *tok = consume(parser);
-      if (tok->type != FZL_TOKTYPE_NAME)
   {
     snprintf(plast_err, sizeof(plast_err),
-                 "'%s': expected name in function definition at %ld:%ld",
+             "'%s': expect class name after 'new' keyword at %ld:%ld",
-                 tok->filename, tok->ln, tok->cn);
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
     return NULL;
   }
 
-      fzl_token_t *lparen = consume(parser);
+  fzl_node_t *node     = fzl_mknode(FZL_NODETYPE_CONSTRUCT, new);
-      if (lparen->type != FZL_TOKTYPE_LPAREN)
+  node->construct.name = objname;
+
+  return node;
+}
+
+// Assignments parsing
+fzl_node_t *parse_assignment(fzl_parser_t *parser)
+{
+  fzl_node_t *left = parse_new(parser);
+  if (!left)
+    return NULL;
+
+  if (is(parser, FZL_TOKTYPE_EQ))
+  {
+    fzl_token_t *asn = consume(parser);
+    if (left->type != FZL_NODETYPE_IDENTIFIER &&
+        left->type != FZL_NODETYPE_DECLARATION &&
+        left->type != FZL_NODETYPE_FIELD)
     {
       snprintf(plast_err, sizeof(plast_err),
-                 "'%s': expected '(' after name at %ld:%ld", lparen->filename,
+               "'%s': cannot assign to '%s' at %ld:%ld", left->token->filename,
-                 lparen->ln, lparen->cn);
+               (char *)left->token->value, asn->ln, asn->cn);
+      return NULL;
+    }
+
+    fzl_node_t *right = parse_assignment(parser);
+    if (!right)
+      return NULL;
+
+    fzl_node_t *node      = fzl_mknode(FZL_NODETYPE_ASSIGN, asn);
+    node->binary_op.left  = left;
+    node->binary_op.right = right;
+
+    left = node;
+  }
+
+  return left;
+}
+
+// Expression parsing
+fzl_node_t *parse_expression(fzl_parser_t *parser)
+{
+  return parse_assignment(parser);
+}
+
+fzl_node_t *parse_statement(fzl_parser_t *parser);
+
+// Parse class definition
+fzl_node_t *parse_class(fzl_parser_t *parser)
+{
+  if (!parser)
+    return NULL;
+
+  fzl_token_t *class = consume(parser);
+  fzl_token_t *name  = consume(parser);
+  if (name->type != FZL_TOKTYPE_NAME)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expected class name at %ld:%ld", name->filename, name->ln,
+             name->cn);
+    return NULL;
+  }
+
+  fzl_token_t *lbrace = consume(parser);
+  if (lbrace->type != FZL_TOKTYPE_LBRACE)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expected '{' after class name at %ld:%ld", lbrace->filename,
+             lbrace->ln, lbrace->cn);
+    return NULL;
+  }
+
+  size_t fremainder   = 2;
+  size_t fcount       = 0;
+  fzl_node_t **fields = malloc(fremainder * sizeof(fzl_node_t *));
+  if (!fields)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "failed to allocate space for class fields");
+    return NULL;
+  }
+
+  size_t mremainder    = 2;
+  size_t mcount        = 0;
+  fzl_node_t **methods = malloc(mremainder * sizeof(fzl_node_t *));
+  if (!methods)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "failed to allocate space for class fields");
+    free(fields);
+    return NULL;
+  }
+
+  while (!is(parser, FZL_TOKTYPE_RBRACE))
+  {
+    fzl_node_t *node = parse_statement(parser);
+    if (!node)
+      return NULL;
+
+    if (node->type == FZL_NODETYPE_DECLARATION)
+    {
+      if (fremainder <= fcount)
+      {
+        fremainder *= 2;
+        fields = realloc(fields, fremainder * sizeof(fzl_node_t *));
+        if (!fields)
+        {
+          snprintf(plast_err, sizeof(plast_err),
+                   "failed to resize fields array");
+          free(methods);
+          return NULL;
+        }
+      }
+
+      fields[fcount++] = node;
+    }
+    else if (node->type == FZL_NODETYPE_FUNCTION)
+    {
+      if (mremainder <= mcount)
+      {
+        mremainder *= 2;
+        methods = realloc(methods, mremainder * sizeof(fzl_node_t *));
+        if (!methods)
+        {
+          snprintf(plast_err, sizeof(plast_err),
+                   "failed to resize methods array");
+          free(fields);
+          return NULL;
+        }
+      }
+
+      fzl_node_t **new_args = realloc(node->fn.args, (++node->fn.args_count) *
+                                                         sizeof(fzl_node_t *));
+      if (!new_args)
+      {
+        snprintf(plast_err, sizeof(plast_err),
+                 "failed to reallocate method args list");
+        free(fields);
+        return NULL;
+      }
+
+      if (node->fn.args_count > 1)
+        memmove(&new_args[1], new_args,
+                (node->fn.args_count - 1) * sizeof(fzl_node_t *));
+
+      fzl_node_t *this_id      = fzl_mknode(FZL_NODETYPE_IDENTIFIER, &this_tok);
+      fzl_node_t *this_dec     = fzl_mknode(FZL_NODETYPE_DECLARATION, name);
+      this_dec->var.type       = name;
+      this_dec->var.identifier = this_id;
+
+      new_args[0]       = this_dec;
+      node->fn.args     = new_args;
+      methods[mcount++] = node;
+    }
+    else
+    {
+      snprintf(plast_err, sizeof(plast_err),
+               "'%s': unknown type of class member at %ld:%ld",
+               node->token->filename, node->token->ln, node->token->cn);
+      free(fields);
+      free(methods);
+      return NULL;
+    }
+  }
+  fzl_token_t *rbra = consume(parser);
+  if (rbra->type != FZL_TOKTYPE_RBRACE)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expected '}' after class definition at %ld:%ld",
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
+    free(fields);
+    free(methods);
+    return NULL;
+  }
+
+  fzl_node_t *node          = fzl_mknode(FZL_NODETYPE_CLASS, class);
+  node->class.name          = name;
+  node->class.fields        = fields;
+  node->class.fields_count  = fcount;
+  node->class.methods       = methods;
+  node->class.methods_count = mcount;
+
+  return node;
+}
+
+// Functions parsing
+fzl_node_t *parse_function(fzl_parser_t *parser)
+{
+  if (!parser)
+    return NULL;
+
+  fzl_token_t *fn = consume(parser);
+  if (fn->type != FZL_TOKTYPE_FUNCTION)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expected keyword 'fn' at %ld:%ld", last_known_tok->filename,
+             last_known_tok->ln, last_known_tok->cn);
+    return NULL;
+  }
+
+  fzl_token_t *name = consume(parser);
+  if (!name || name->type != FZL_TOKTYPE_NAME)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expected function name at %ld:%ld",
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
+    return NULL;
+  }
+
+  fzl_token_t *lpar = consume(parser);
+  if (!lpar || lpar->type != FZL_TOKTYPE_LPAREN)
+  {
+    snprintf(plast_err, sizeof(plast_err), "'%s': expected '(' at %ld:%ld",
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
     return NULL;
   }
 
@@ -597,20 +827,27 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
       consume(parser);
   }
 
-      fzl_token_t *rparen = consume(parser);
+  fzl_token_t *rpar = consume(parser);
-      if (rparen->type != FZL_TOKTYPE_RPAREN)
+  if (!rpar || rpar->type != FZL_TOKTYPE_RPAREN)
   {
     snprintf(plast_err, sizeof(plast_err),
              "'%s': expected ')' after argument list at %ld:%ld",
-                 rparen->filename, rparen->ln, rparen->cn);
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
     return NULL;
   }
 
+  fzl_token_t *type = NULL;
+  if (is(parser, FZL_TOKTYPE_TYPE) || is(parser, FZL_TOKTYPE_NAME))
+    type = consume(parser);
+
+  if (!type)
+    type = &null_tok;
+
   if (!is(parser, FZL_TOKTYPE_LBRACE))
   {
-        fzl_token_t *tok = peek(parser);
+    snprintf(plast_err, sizeof(plast_err),
-        snprintf(plast_err, sizeof(plast_err), "'%s': expected '{' at %ld:%ld",
+             "'%s': expected '{' after function declaration at %ld:%ld",
-                 tok->filename, tok->ln, tok->cn);
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
     return NULL;
   }
 
@@ -618,77 +855,22 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
   if (!body)
     return NULL;
 
-      fzl_node_t *node    = fzl_mknode(FZL_NODETYPE_FUNCTION, tok);
+  fzl_node_t *node    = fzl_mknode(FZL_NODETYPE_FUNCTION, name);
   node->fn.args       = args;
   node->fn.args_count = count;
   node->fn.body       = body;
-      node->fn.name       = tok;
+  node->fn.name       = name;
   node->fn.type       = type;
 
   return node;
 }
-    else if (type->type == FZL_TOKTYPE_TYPE ||
-             next(parser)->type == FZL_TOKTYPE_EQ)
-    {
 
-      fzl_node_t *identifier = parse_primary(parser);
+// Return parsing
-      if (!identifier || identifier->type != FZL_NODETYPE_IDENTIFIER)
+fzl_node_t *parse_return(fzl_parser_t *parser)
 {
-        snprintf(plast_err, sizeof(plast_err),
+  if (!parser)
-                 "'%s': expected identifier at %ld:%ld", type->filename,
-                 type->ln, type->cn);
-        return NULL;
-      }
-
-      fzl_node_t *left     = fzl_mknode(FZL_NODETYPE_DECLARATION, type);
-      left->var.type       = type;
-      left->var.identifier = identifier;
-
-      if (is(parser, FZL_TOKTYPE_EQ))
-      {
-        fzl_node_t *right;
-        while (is(parser, FZL_TOKTYPE_EQ))
-        {
-          fzl_token_t *asn = consume(parser);
-          right            = parse_expression(parser);
-          if (!right)
     return NULL;
 
-          fzl_node_t *node      = fzl_mknode(FZL_NODETYPE_ASSIGN, asn);
-          node->binary_op.left  = left;
-          node->binary_op.right = right;
-
-          left = node;
-        }
-      }
-
-      res = left;
-    }
-  }
-  else if (is(parser, FZL_TOKTYPE_NAME) && next(parser)->type == FZL_TOKTYPE_EQ)
-  {
-    fzl_token_t *name = consume(parser);
-    fzl_node_t *left  = fzl_mknode(FZL_NODETYPE_IDENTIFIER, name);
-
-    while (is(parser, FZL_TOKTYPE_EQ))
-    {
-      fzl_token_t *eq = consume(parser);
-
-      fzl_node_t *right = parse_expression(parser);
-      if (!right)
-        return NULL;
-
-      fzl_node_t *assn      = fzl_mknode(FZL_NODETYPE_ASSIGN, eq);
-      assn->binary_op.left  = left;
-      assn->binary_op.right = right;
-
-      left = assn;
-    }
-
-    res = left;
-  }
-  else if (is(parser, FZL_TOKTYPE_RETURN))
-  {
   fzl_token_t *ret = consume(parser);
   fzl_node_t *node = fzl_mknode(FZL_NODETYPE_RETURN, ret);
 
@@ -701,17 +883,21 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
     node->ret.value = retval;
   }
 
-    res = node;
+  return node;
 }
-  else if (is(parser, FZL_TOKTYPE_IF))
+
+fzl_node_t *parse_if(fzl_parser_t *parser)
 {
+  if (!parser)
+    return NULL;
+
   fzl_token_t *if_tok = consume(parser);
   fzl_token_t *lparen = consume(parser);
   if (lparen->type != FZL_TOKTYPE_LPAREN)
   {
     snprintf(plast_err, sizeof(plast_err),
-               "'%s': expected '(' before condition at %ld:%ld",
+             "'%s': expected '(' before condition at %ld:%ld", lparen->filename,
-               lparen->filename, lparen->ln, lparen->cn);
+             lparen->ln, lparen->cn);
     return NULL;
   }
 
@@ -723,8 +909,8 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
   if (rparen->type != FZL_TOKTYPE_RPAREN)
   {
     snprintf(plast_err, sizeof(plast_err),
-               "'%s': expected ')' after condition at %ld:%ld",
+             "'%s': expected ')' after condition at %ld:%ld", rparen->filename,
-               rparen->filename, rparen->ln, rparen->cn);
+             rparen->ln, rparen->cn);
     return NULL;
   }
 
@@ -748,8 +934,13 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
 
   return stmt_node;
 }
-  else if (is(parser, FZL_TOKTYPE_LBRACE))
+
+// Block statement parsing
+fzl_node_t *parse_block(fzl_parser_t *parser)
 {
+  if (!parser)
+    return NULL;
+
   fzl_token_t *block_tok = consume(parser);
 
   size_t remainder   = 2;
@@ -785,12 +976,30 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
   return node;
 }
 
+// Statement parsing
+fzl_node_t *parse_statement(fzl_parser_t *parser)
+{
+  if (!peek(parser))
+    return NULL;
+
+  fzl_node_t *res = NULL;
+
+  if (is(parser, FZL_TOKTYPE_CLASS))
+    return parse_class(parser);
+  else if (is(parser, FZL_TOKTYPE_FUNCTION))
+    return parse_function(parser);
+  else if (is(parser, FZL_TOKTYPE_RETURN))
+    res = parse_return(parser);
+  else if (is(parser, FZL_TOKTYPE_IF))
+    return parse_if(parser);
+  else if (is(parser, FZL_TOKTYPE_LBRACE))
+    return parse_block(parser);
+
   if (!res)
     res = parse_expression(parser);
 
   if (!is(parser, FZL_TOKTYPE_SEMICOLON))
   {
-    printf("Current token are %d\n", last_known_tok->type);
     snprintf(plast_err, sizeof(plast_err), "'%s': missing ';' at %ld:%ld",
              last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
     return NULL;
@@ -804,6 +1013,9 @@ fzl_node_t *parse_statement(fzl_parser_t *parser)
 // Internal parsing entry point
 fzl_node_t *parse_program(fzl_parser_t *parser)
 {
+  if (!peek(parser))
+    return NULL;
+
   fzl_node_t *first = NULL;
   fzl_node_t *last  = NULL;
   fzl_node_t *node  = NULL;
@@ -837,6 +1049,8 @@ fzl_node_t *parse_program(fzl_parser_t *parser)
 // Parse tokens and build AST
 int fzl_parse(fzl_parser_t *parser)
 {
+  last_known_tok = NULL;
+
   fzl_node_t *ast = parse_program(parser);
   if (!ast)
     return -1;
@@ -863,8 +1077,13 @@ void fzl_freeast(fzl_node_t *root)
 
   while (root)
   {
-    if (root->type == FZL_NODETYPE_BLOCK)
+    switch (root->type)
     {
+      case FZL_NODETYPE_IDENTIFIER:
+      case FZL_NODETYPE_LITERAL:
+        break;
+
+      case FZL_NODETYPE_BLOCK:
         if (root->list.entries)
         {
           for (size_t i = 0; i < root->list.entry_count; i++)
@@ -873,44 +1092,104 @@ void fzl_freeast(fzl_node_t *root)
 
           free(root->list.entries);
         }
-    }
+        break;
-    else if (root->type == FZL_NODETYPE_CALL)
+
-    {
+      case FZL_NODETYPE_CALL:
+        if (root->call.callee)
+          fzl_freeast(root->call.callee);
+
         if (root->call.args_count)
         {
           for (size_t i = 0; i < root->call.args_count; i++)
             if (root->call.args[i])
               fzl_freeast(root->call.args[i]);
-
+        }
+        if (root->call.args)
           free(root->call.args);
-      }
+        break;
-    }
+
-    else if (root->type == FZL_NODETYPE_ADD || root->type == FZL_NODETYPE_SUB ||
+      case FZL_NODETYPE_CONDITIONAL:
-             root->type == FZL_NODETYPE_MUL || root->type == FZL_NODETYPE_DIV ||
+        if (root->cond.condition)
-             root->type == FZL_NODETYPE_POW || root->type == FZL_NODETYPE_MOD)
+          fzl_freeast(root->cond.condition);
-    {
+
+        if (root->cond.true_block)
+          fzl_freeast(root->cond.true_block);
+
+        if (root->cond.else_block)
+          fzl_freeast(root->cond.else_block);
+        break;
+
+      case FZL_NODETYPE_ADD:
+      case FZL_NODETYPE_SUB:
+      case FZL_NODETYPE_MUL:
+      case FZL_NODETYPE_DIV:
+      case FZL_NODETYPE_POW:
+      case FZL_NODETYPE_MOD:
+      case FZL_NODETYPE_OR:
+      case FZL_NODETYPE_AND:
+      case FZL_NODETYPE_EQUAL:
+      case FZL_NODETYPE_NEQUAL:
+      case FZL_NODETYPE_LESS:
+      case FZL_NODETYPE_LESS_EQUAL:
+      case FZL_NODETYPE_GREATER:
+      case FZL_NODETYPE_GREATER_EQUAL:
+      case FZL_NODETYPE_ASSIGN:
         if (root->binary_op.left)
           fzl_freeast(root->binary_op.left);
         if (root->binary_op.right)
           fzl_freeast(root->binary_op.right);
-    }
+        break;
-    else if (root->type == FZL_NODETYPE_UNARY_PLUS ||
+
-             root->type == FZL_NODETYPE_UNARY_MINUS)
+      case FZL_NODETYPE_UNARY_PLUS:
-    {
+      case FZL_NODETYPE_UNARY_MINUS:
+      case FZL_NODETYPE_NOT:
         if (root->unary_op.operand)
           fzl_freeast(root->unary_op.operand);
-    }
+        break;
-    else if (root->type == FZL_NODETYPE_FUNCTION)
+
-    {
+      case FZL_NODETYPE_FUNCTION:
         if (root->fn.args_count)
           for (size_t i = 0; i < root->fn.args_count; i++)
-          fzl_freenode(root->fn.args[i]);
+            fzl_freeast(root->fn.args[i]);
         free(root->fn.args);
-      fzl_freenode(root->fn.body);
+        fzl_freeast(root->fn.body);
+        break;
+
+      case FZL_NODETYPE_RETURN:
+        if (root->ret.value)
+          fzl_freeast(root->ret.value);
+        break;
+
+      case FZL_NODETYPE_CLASS:
+        if (root->class.fields_count)
+          for (size_t i = 0; i < root->class.fields_count; i++)
+            fzl_freeast(root->class.fields[i]);
+        free(root->class.fields);
+
+        if (root->class.methods_count)
+          for (size_t i = 0; i < root->class.methods_count; i++)
+            fzl_freeast(root->class.methods[i]);
+        free(root->class.methods);
+        break;
+
+      case FZL_NODETYPE_CONSTRUCT:
+        fzl_freeast(root->construct.name);
+        break;
+
+      case FZL_NODETYPE_FIELD:
+        fzl_freeast(root->memb.field);
+        fzl_freeast(root->memb.parent);
+        break;
+
+      case FZL_NODETYPE_DECLARATION:
+        if (root->var.identifier)
+          fzl_freeast(root->var.identifier);
+        break;
     }
 
+    fzl_node_t *next = root->next;
     fzl_freenode(root);
-    root = root->next;
+    root = next;
   }
 }
 

src/compiler/fzl_reader.c

@@ -70,7 +70,15 @@ fzl_token_t *parse_name(fzl_reader_t *reader)
     return NULL;
   }
 
-  if (strcmp(value, "return") == 0)
+  if (strcmp(value, "class") == 0)
+    tok =
+        fzl_mktoken(FZL_TOKTYPE_CLASS, l.line, l.col, value, size, l.filename);
+  else if (strcmp(value, "new") == 0)
+    tok = fzl_mktoken(FZL_TOKTYPE_NEW, l.line, l.col, value, size, l.filename);
+  else if (strcmp(value, "fn") == 0)
+    tok = fzl_mktoken(FZL_TOKTYPE_FUNCTION, l.line, l.col, value, size,
+                      l.filename);
+  else if (strcmp(value, "return") == 0)
     tok =
         fzl_mktoken(FZL_TOKTYPE_RETURN, l.line, l.col, value, size, l.filename);
   else if (strcmp(value, "if") == 0)
@@ -80,6 +88,9 @@ fzl_token_t *parse_name(fzl_reader_t *reader)
   else if (strcmp(value, "true") == 0 || strcmp(value, "false") == 0)
     tok = fzl_mktoken(FZL_TOKTYPE_BOOL_LITERAL, l.line, l.col, value, size,
                       l.filename);
+  else if (strcmp(value, "null") == 0)
+    tok = fzl_mktoken(FZL_TOKTYPE_NULL_LITERAL, l.line, l.col, value, size,
+                      l.filename);
   else if (strcmp(value, "str") == 0 || strcmp(value, "char") == 0 ||
            strcmp(value, "bool") == 0 || strcmp(value, "uint") == 0 ||
            strcmp(value, "int") == 0 || strcmp(value, "i8") == 0 ||
@@ -193,31 +204,31 @@ fzl_token_t *parse_number(fzl_reader_t *reader)
 // Add single-char token
 fzl_token_t *add_single(fzl_reader_t *reader, fzl_toktype_t type)
 {
-  size_t p = move(reader, 1);
   fzl_file_loc l;
-  bool ok = fzl_linked_getpos(reader->linked, p, &l);
+  bool ok = fzl_linked_getpos(reader->linked, reader->position, &l);
   if (!ok)
   {
     snprintf(last_err, sizeof(last_err), "failed to locate line:col");
     return NULL;
   }
 
-  return fzl_mktoken(type, l.line, l.col, NULL, 0, l.filename);
+  move(reader, 1);
+  return fzl_mktoken(type, l.line, l.col, "", 0, l.filename);
 }
 
 // Add double-char token
 fzl_token_t *add_double(fzl_reader_t *reader, fzl_toktype_t type)
 {
-  size_t p = move(reader, 2);
   fzl_file_loc l;
-  bool ok = fzl_linked_getpos(reader->linked, p, &l);
+  bool ok = fzl_linked_getpos(reader->linked, reader->position, &l);
   if (!ok)
   {
     snprintf(last_err, sizeof(last_err), "failed to locate line:col");
     return NULL;
   }
 
-  return fzl_mktoken(type, l.line, l.col, NULL, 0, l.filename);
+  move(reader, 2);
+  return fzl_mktoken(type, l.line, l.col, "", 0, l.filename);
 }
 
 // Skip symbols until '\n' or EOF
@@ -286,6 +297,8 @@ int fzl_read(fzl_reader_t *reader)
       token = add_single(reader, FZL_TOKTYPE_RPAREN);
     else if (curr == ',')
       token = add_single(reader, FZL_TOKTYPE_COMMA);
+    else if (curr == '.')
+      token = add_single(reader, FZL_TOKTYPE_DOT);
     else if (curr == '*')
       token = add_single(reader, FZL_TOKTYPE_STAR);
     else if (curr == '/')
@@ -300,7 +313,7 @@ int fzl_read(fzl_reader_t *reader)
       token = add_single(reader, FZL_TOKTYPE_PERCENT);
     else if (curr == '=')
       token = add_single(reader, FZL_TOKTYPE_EQ);
-    else if (curr >= 'A' && curr <= 'Z' || curr >= 'a' && curr <= 'z' ||
+    else if ((curr >= 'A' && curr <= 'Z') || (curr >= 'a' && curr <= 'z') ||
              curr == '_')
       token = parse_name(reader);
     else if (curr >= '0' && curr <= '9')
@@ -340,6 +353,7 @@ int fzl_read(fzl_reader_t *reader)
     }
 
     fzl_reader_ll_t *tok_node = malloc(sizeof(fzl_reader_ll_t));
+    tok_node->next            = NULL;
     tok_node->token           = token;
 
     reader->last->next = tok_node;

src/compiler/fzl_token.c

@@ -6,15 +6,20 @@
 fzl_token_t *fzl_mktoken(const fzl_toktype_t type, size_t line, size_t col,
                          void *value, size_t value_len, char *filename)
 {
-  char *valholder = malloc(value_len + 1);
+  char *valholder = NULL;
+
+  if (value && value_len > 0)
+  {
+    valholder = malloc(value_len + 1);
     memcpy(valholder, value, value_len);
     valholder[value_len] = '\0';
+  }
 
   fzl_token_t *token = malloc(sizeof(fzl_token_t));
   token->type        = type;
   token->ln          = line;
   token->cn          = col;
-  token->store_value = value_len > 0;
+  token->store_value = (valholder != NULL);
   token->value       = valholder;
   token->value_sz    = value_len;
   token->filename    = filename;

src/compiler/fzl_walker.c

@@ -5,6 +5,7 @@
 #include <compiler/fzl_token.h>
 #include <compiler/fzl_walker.h>
 #include <compiler/utils/fzl_const_pool.h>
+#include <compiler/utils/fzl_ctable.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -13,6 +14,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+char *null_name = "<null>";
 char wlast_err[256];
 
 fzl_walker_t *fzl_mkwalker(fzl_node_t *root)
@@ -53,6 +55,8 @@ fzl_walker_t *fzl_mkwalker(fzl_node_t *root)
   }
 
   walker->ctx           = NULL;
+  walker->classes_count = 0;
+  memset(walker->classes, 0, sizeof(walker->classes));
 
   return walker;
 }
@@ -60,8 +64,11 @@ fzl_walker_t *fzl_mkwalker(fzl_node_t *root)
 // --- Walking zone ---
 
 // Convert type token to `fzl_type_t`
-const fzl_type_t tok_to_type(fzl_token_t *tok)
+fzl_type_t tok_to_type(fzl_token_t *tok)
 {
+  if (tok->type == FZL_TOKTYPE_NAME)
+    return FZL_TYPE_OBJECT;
+
   if (strcmp((char *)tok->value, "i8") == 0)
     return FZL_TYPE_INT8;
   if (strcmp((char *)tok->value, "i16") == 0)
@@ -95,14 +102,53 @@ const fzl_type_t tok_to_type(fzl_token_t *tok)
   return FZL_TYPE_NULL;
 }
 
-static bool is_compatible(fzl_type_t t1, fzl_type_t t2)
+static bool is_compatible(fzl_type_t t1, fzl_type_t t2, char *c1, char *c2)
 {
+  if (t1 == FZL_TYPE_OBJECT || t2 == FZL_TYPE_OBJECT)
+  {
+    bool classes_compatible = strcmp(c1, c2) == 0 ||
+                              strcmp(c1, null_name) == 0 ||
+                              strcmp(c2, null_name) == 0;
+
+    return t1 == FZL_TYPE_OBJECT && t2 == FZL_TYPE_OBJECT && classes_compatible;
+  }
+
   if (t1 == t2)
     return true;
 
   return t1 >= FZL_TYPE_INT8 && t2 >= FZL_TYPE_INT8;
 }
 
+// Add one layer of ctx
+fzl_walk_ctx_t *nest_ctx(fzl_walker_t *walker, fzl_walk_ctx_type_t type)
+{
+  if (!walker)
+    return NULL;
+
+  fzl_walk_ctx_t *newctx = malloc(sizeof(fzl_walk_ctx_t));
+  if (!newctx)
+    return NULL;
+
+  newctx->type   = type;
+  newctx->parent = walker->ctx;
+  walker->ctx    = newctx;
+
+  return walker->ctx;
+}
+
+// Go outside current ctx and then clean it
+fzl_walk_ctx_t *fin_ctx(fzl_walker_t *walker)
+{
+  if (!walker)
+    return NULL;
+
+  fzl_walk_ctx_t *curr = walker->ctx;
+  walker->ctx          = walker->ctx->parent;
+
+  free(curr);
+  return walker->ctx;
+}
+
 // Add const to consts table
 size_t add_const(fzl_walker_t *walker, fzl_const_t c)
 {
@@ -154,6 +200,168 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
   {
     switch (node->type)
     {
+      case FZL_NODETYPE_CLASS:
+      {
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_CLASS);
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        newctx->fn              = node;
+        newctx->initial_env_lvl = walker->sym_top;
+
+        walker->classes[walker->classes_count] =
+            fzl_mkctable(node->class.name->value);
+        fzl_ctable_t *class = walker->classes[walker->classes_count++];
+        class->name         = node->class.name->value;
+
+        for (size_t i = 0; i < node->class.fields_count; i++)
+        {
+          if (class->fields_remainder <= class->fields_count)
+          {
+            class->fields_remainder *= 2;
+            class->fields =
+                realloc(class->fields,
+                        class->fields_remainder * sizeof(fzl_ctable_field_t));
+          }
+
+          class->fields[class->fields_count] = (fzl_ctable_field_t){
+              .name       = node->class.fields[i]->var.identifier->token->value,
+              .type       = tok_to_type(node->class.fields[i]->var.type),
+              .slot_index = class->fields_count++};
+        }
+
+        for (size_t i = 0; i < node->class.methods_count; i++)
+        {
+          fzl_node_t *fn = node->class.methods[i];
+
+          size_t classname_len = strlen(class->name);
+          size_t fnname_len    = strlen(fn->fn.name->value);
+          char *method_name    = malloc(classname_len + fnname_len + 2);
+
+          strcpy(method_name, class->name);
+          method_name[classname_len] = '_';
+          strcpy((method_name + classname_len + 1), fn->fn.name->value);
+          method_name[classname_len + fnname_len + 1] = 0;
+
+          if (fn->fn.name->value)
+            free(fn->fn.name->value);
+
+          fn->fn.name->value   = method_name;
+          fzl_walk_res_t fnres = walk(walker, fn);
+          if (fnres.error)
+            return fnres;
+        }
+
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        current_res = (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
+        break;
+      }
+
+      case FZL_NODETYPE_CONSTRUCT:
+      {
+        fzl_node_t *classname = node->construct.name;
+        fzl_ctable_t *ct      = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp((char *)classname->token->value,
+                     walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+        if (!ct)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': class '%s' not found (at %ld:%ld)",
+                   classname->token->filename, (char *)classname->token->value,
+                   classname->token->ln, classname->token->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        push_op(walker, FZL_OPCODE_ALLOC_OBJECT);
+        push_word(walker, ct->fields_count);
+
+        current_res = (fzl_walk_res_t){
+            .type = FZL_TYPE_OBJECT, .error = false, .classname = ct->name};
+        break;
+      }
+
+      case FZL_NODETYPE_FIELD:
+      {
+        fzl_walk_res_t parent_res = walk(walker, node->memb.parent);
+        if (parent_res.error)
+          return parent_res;
+
+        if (parent_res.type != FZL_TYPE_OBJECT || !parent_res.classname)
+        {
+          fzl_token_t *tok = node->memb.parent->token;
+          snprintf(
+              wlast_err, sizeof(wlast_err),
+              "'%s': cannot access field '%s' on non-object type at %ld:%ld",
+              tok->filename, (char *)node->memb.field->token->value, tok->ln,
+              tok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        fzl_ctable_t *ct = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp(parent_res.classname, walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+
+        if (!ct)
+        {
+          fzl_token_t *tok = node->memb.parent->token;
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': access to unknown class '%s' at %ld:%ld",
+                   tok->filename, (char *)tok->value, tok->ln, tok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        fzl_token_t *ftok = node->memb.field->token;
+        fzl_ctable_field_t ctf;
+        bool field_exists = false;
+        for (size_t i = 0; i < ct->fields_count; i++)
+        {
+          if (strcmp(ftok->value, ct->fields[i].name) == 0)
+          {
+            field_exists = true;
+            ctf          = ct->fields[i];
+            break;
+          }
+        }
+
+        if (!field_exists)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': cannot find field '%s' in class '%s' at %ld:%ld",
+                   ftok->filename, (char *)ftok->value, parent_res.classname,
+                   ftok->ln, ftok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        push_op(walker, FZL_OPCODE_GET_FIELD);
+        push_word(walker, ctf.slot_index);
+
+        current_res = (fzl_walk_res_t){.type      = ctf.type,
+                                       .error     = false,
+                                       .classname = parent_res.classname};
+        break;
+      }
+
       case FZL_NODETYPE_FUNCTION:
       {
         push_op(walker, FZL_OPCODE_JMP);
@@ -164,6 +372,7 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         fzl_symtable_res_t putres =
             fzl_symt_put(walker->syms[walker->sym_top - 1],
                          node->fn.name->value, fntype, walker->op_count);
+
         if (putres != FZL_SYMTABLE_RESULT_OK)
         {
           if (putres == FZL_SYMTABLE_RESULT_EXISTS)
@@ -177,15 +386,39 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
                      "'%s': failed to store name '%s'", node->fn.name->filename,
                      (char *)node->fn.name->value);
 
-          return (fzl_walk_res_t){.error = true};
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        if (fntype == FZL_TYPE_OBJECT)
+        {
+          fzl_symtable_res_t updres =
+              fzl_symt_setobjclass(walker->syms[walker->sym_top - 1],
+                                   node->fn.name->value, node->fn.type->value);
+          if (updres != FZL_SYMTABLE_RESULT_OK)
+          {
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "'%s': failed to assign object type to function return "
+                     "type at %ld:%ld",
+                     node->fn.type->filename, node->fn.type->ln,
+                     node->fn.type->cn);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
         }
 
         // NOTE: add sym_top limit check
-        size_t lvl                      = walker->sym_top;
+        ssize_t lvl                     = walker->sym_top;
         walker->syms[walker->sym_top++] = fzl_mksymt();
-        walker->ctx                     = malloc(sizeof(fzl_walk_ctx_t));
+
-        walker->ctx->fn                 = node;
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_FN);
-        walker->ctx->initial_env_lvl    = lvl;
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        newctx->type            = FZL_WALK_CTX_TYPE_FN;
+        newctx->fn              = node;
+        newctx->initial_env_lvl = lvl;
 
         push_op(walker, FZL_OPCODE_MK_ENVTABLE);
 
@@ -205,18 +438,30 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         // near future
 
         push_op(walker, FZL_OPCODE_RM_ENVTABLE);
+        push_op(walker, FZL_OPCODE_RET);
         walker->ops[skip_ip] = walker->op_count;
 
-        walker->ctx = NULL; // NOTE: think about nested function defs (not now)
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
         for (ssize_t i = walker->sym_top - 1; i >= lvl; i--)
           fzl_freesymt(walker->syms[--walker->sym_top]);
 
+        char *retclass = NULL;
+        if (fntype == FZL_TYPE_OBJECT && node->fn.type)
+          retclass = node->fn.type->value;
+
+        current_res = (fzl_walk_res_t){
+            .type = fntype, .error = false, .classname = retclass};
         break;
       }
 
       case FZL_NODETYPE_RETURN:
       {
-        if (!walker->ctx)
+        if (!walker->ctx || walker->ctx->type != FZL_WALK_CTX_TYPE_FN)
         {
           snprintf(
               wlast_err, sizeof(wlast_err),
@@ -225,14 +470,16 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
         }
 
+        bool returning_object = false;
         if (node->ret.value)
         {
           fzl_walk_res_t retres = walk(walker, node->ret.value);
           if (retres.error)
             return retres;
 
-          if (!is_compatible(retres.type,
+          fzl_node_t *fn_node = walker->ctx->fn;
-                             tok_to_type(walker->ctx->fn->fn.type)))
+          if (!is_compatible(retres.type, tok_to_type(fn_node->fn.type),
+                             retres.classname, walker->ctx->fn->fn.type->value))
           {
             snprintf(
                 wlast_err, sizeof(wlast_err),
@@ -242,14 +489,23 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
           }
 
-          current_res = (fzl_walk_res_t){.type = retres.type, .error = false};
+          if (retres.type == FZL_TYPE_OBJECT)
+            returning_object = true;
+
+          current_res = (fzl_walk_res_t){.type      = retres.type,
+                                         .error     = false,
+                                         .classname = retres.classname};
         }
         else
           current_res = (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
 
         for (size_t i = 0; i < (walker->sym_top - walker->ctx->initial_env_lvl);
              i++)
+        {
+          if (returning_object)
+            push_op(walker, FZL_OPCODE_ESCAPE_OBJECT);
           push_op(walker, FZL_OPCODE_RM_ENVTABLE);
+        }
         push_op(walker, FZL_OPCODE_RET);
         break;
       }
@@ -280,7 +536,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         if (right.error)
           return right;
 
-        if (!is_compatible(left.type, right.type))
+        if (!is_compatible(left.type, right.type, left.classname,
+                           right.classname))
         {
           snprintf(wlast_err, sizeof(wlast_err),
                    "'%s': incompatible types at %ld:%ld", node->token->filename,
@@ -288,6 +545,46 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
         }
 
+        if (left.type == FZL_TYPE_STRING && right.type == FZL_TYPE_STRING)
+        {
+          switch (node->type)
+          {
+            case FZL_NODETYPE_EQUAL:
+              push_op(walker, FZL_OPCODE_CMP_EQ_STR);
+              break;
+
+            case FZL_NODETYPE_NEQUAL:
+              push_op(walker, FZL_OPCODE_CMP_NEQ_STR);
+              break;
+
+            default:
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': unsupported strings operation at %ld:%ld",
+                       node->token->filename, node->token->ln, node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+        }
+        else if (left.type == FZL_TYPE_OBJECT && right.type == FZL_TYPE_OBJECT)
+        {
+          switch (node->type)
+          {
+            case FZL_NODETYPE_EQUAL:
+              push_op(walker, FZL_OPCODE_CMP_EQ_OBJ);
+              break;
+
+            case FZL_NODETYPE_NEQUAL:
+              push_op(walker, FZL_OPCODE_CMP_NEQ_OBJ);
+              break;
+
+            default:
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': unsupported object operation at %ld:%ld",
+                       node->token->filename, node->token->ln, node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+        }
+        else
+        {
           switch (node->type)
           {
             case FZL_NODETYPE_EQUAL:
@@ -311,8 +608,9 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             default:
               break;
           }
+        }
 
-        current_res = (fzl_walk_res_t){.type = left.type, .error = false};
+        current_res = (fzl_walk_res_t){.type = FZL_TYPE_BOOL, .error = false};
         break;
       }
 
@@ -327,7 +625,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         if (right.error)
           return right;
 
-        if (!is_compatible(left.type, right.type))
+        if (!is_compatible(left.type, right.type, left.classname,
+                           right.classname))
         {
           snprintf(wlast_err, sizeof(wlast_err),
                    "'%s': incompatible types at %ld:%ld", node->token->filename,
@@ -340,7 +639,7 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         else
           push_op(walker, FZL_OPCODE_OR);
 
-        current_res = (fzl_walk_res_t){.type = left.type, .error = false};
+        current_res = (fzl_walk_res_t){.type = FZL_TYPE_BOOL, .error = false};
         break;
       }
 
@@ -415,7 +714,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         push_word(walker, n);
         push_op(walker, FZL_OPCODE_LOOKUP_ENV);
 
-        current_res = (fzl_walk_res_t){.type = sym.type, .error = false};
+        current_res = (fzl_walk_res_t){
+            .type = sym.type, .error = false, .classname = sym.classname};
         break;
       }
 
@@ -434,6 +734,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         break;
 
       case FZL_NODETYPE_CALL:
+        if (strcmp(node->token->value, "printline") == 0)
+        {
           if (node->call.args_count > 0)
           {
             for (size_t i = 0; i < node->call.args_count; i++)
@@ -444,8 +746,6 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             }
           }
 
-        if (strcmp(node->token->value, "printline") == 0)
-        {
           push_op(walker, FZL_OPCODE_CALL_BUILTIN);
           push_word(walker, FZL_BUILTIN_PRINTLINE);
           if (node->call.args_count < 1)
@@ -457,8 +757,44 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           }
           current_res = (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
         }
+        else if (strcmp(node->token->value, "exit") == 0)
+        {
+          if (node->call.args_count > 0)
+          {
+            for (size_t i = 0; i < node->call.args_count; i++)
+            {
+              fzl_walk_res_t res = walk(walker, node->call.args[i]);
+              if (res.error)
+                return res;
+            }
+
+            push_op(walker, FZL_OPCODE_CALL_BUILTIN);
+            push_word(walker, FZL_BUILTIN_EXIT);
+            if (node->call.args_count < 1)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': 'exit' call with zero arguments at %ld:%ld",
+                       node->token->filename, node->token->ln, node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+            current_res =
+                (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
+          }
+        }
         else
         {
+          if (node->call.callee->type == FZL_NODETYPE_IDENTIFIER)
+          {
+            if (node->call.args_count > 0)
+            {
+              for (size_t i = 0; i < node->call.args_count; i++)
+              {
+                fzl_walk_res_t res = walk(walker, node->call.args[i]);
+                if (res.error)
+                  return res;
+              }
+            }
+
             fzl_sym_t res;
             bool found = false;
             for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
@@ -469,8 +805,9 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             if (!found)
             {
               snprintf(wlast_err, sizeof(wlast_err),
-                     "call to unknown function '%s'",
+                       "'%s': call to unknown function '%s' at %ld:%ld",
-                     (char *)node->token->value);
+                       node->token->filename, (char *)node->token->value,
+                       node->token->ln, node->token->cn);
               return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
             }
 
@@ -484,7 +821,92 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             push_op(walker, FZL_OPCODE_CALL);
             push_word(walker, res.ip);
 
-          current_res = (fzl_walk_res_t){.type = res.type, .error = false};
+            current_res = (fzl_walk_res_t){
+                .type = res.type, .error = false, .classname = res.classname};
+          }
+          else if (node->call.callee->type == FZL_NODETYPE_FIELD)
+          {
+            fzl_node_t *parent_node = node->call.callee->memb.parent;
+            fzl_node_t *method_node = node->call.callee->memb.field;
+
+            fzl_walk_res_t parent_res = walk(walker, parent_node);
+            if (parent_res.error)
+              return parent_res;
+
+            if (parent_res.type != FZL_TYPE_OBJECT || !parent_res.classname)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': cannot call method on non-object type at %ld:%ld",
+                       parent_node->token->filename, parent_node->token->ln,
+                       parent_node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            char *classname   = parent_res.classname;
+            bool class_exists = false;
+            for (size_t i = 0; i < walker->classes_count; i++)
+            {
+              if (strcmp(classname, walker->classes[i]->name) == 0)
+              {
+                class_exists = true;
+                break;
+              }
+            }
+
+            if (!class_exists)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': class '%s' not found (at %ld:%ld)",
+                       parent_node->token->filename, classname,
+                       parent_node->token->ln, parent_node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            size_t classlen  = strlen(classname);
+            size_t fnlen     = strlen(method_node->token->value);
+            char *methodname = malloc(classlen + fnlen + 2);
+            strcpy(methodname, classname);
+            strcpy((methodname + classlen + 1),
+                   node->call.callee->token->value);
+            methodname[classlen]             = '_';
+            methodname[classlen + fnlen + 1] = 0;
+
+            fzl_sym_t fn_sym;
+            bool found_method = false;
+            for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+              if ((found_method =
+                       fzl_symt_get(walker->syms[i], methodname, &fn_sym)))
+                break;
+
+            if (!found_method)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': class '%s' has no method '%s' at %ld:%ld",
+                       node->token->filename, classname,
+                       (char *)node->call.callee->token->value, node->token->ln,
+                       node->token->cn);
+              free(methodname);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+            free(methodname);
+
+            if (node->call.args_count > 0)
+            {
+              for (size_t i = 0; i < node->call.args_count; i++)
+              {
+                fzl_walk_res_t res = walk(walker, node->call.args[i]);
+                if (res.error)
+                  return res;
+              }
+            }
+
+            push_op(walker, FZL_OPCODE_CALL);
+            push_word(walker, fn_sym.ip);
+
+            current_res = (fzl_walk_res_t){.type      = fn_sym.type,
+                                           .error     = false,
+                                           .classname = fn_sym.classname};
+          }
         }
         break;
 
@@ -518,6 +940,14 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           push_word(walker, val);
           current_res = (fzl_walk_res_t){.type = FZL_TYPE_BOOL, .error = false};
         }
+        else if (node->token->type == FZL_TOKTYPE_NULL_LITERAL)
+        {
+          push_op(walker, FZL_OPCODE_PUSHNUM);
+          push_word(walker, 0);
+          push_op(walker, FZL_OPCODE_DEREFERENCE);
+          current_res = (fzl_walk_res_t){
+              .type = FZL_TYPE_OBJECT, .error = false, .classname = null_name};
+        }
         break;
 
       case FZL_NODETYPE_ADD:
@@ -604,9 +1034,33 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
 
       case FZL_NODETYPE_DECLARATION:
       {
+        fzl_ctable_t *ct = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp(node->var.type->value, walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+
         fzl_symtable_res_t res = fzl_symt_put(
             walker->syms[walker->sym_top - 1],
-            node->var.identifier->token->value, tok_to_type(node->var.type), 0);
+            node->var.identifier->token->value,
+            ct != NULL ? FZL_TYPE_OBJECT : tok_to_type(node->var.type), 0);
+
+        if (ct)
+          fzl_symt_setobjclass(walker->syms[walker->sym_top - 1],
+                               node->var.identifier->token->value, ct->name);
+
+        if (res != FZL_SYMTABLE_RESULT_OK)
+        {
+          fzl_token_t *tok = node->var.identifier->token;
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': cannot store '%s' at %ld:%ld", tok->filename,
+                   (char *)tok->value, tok->ln, tok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
 
         fzl_token_t *id_tok = node->var.identifier->token;
         size_t const_n      = add_const(
@@ -621,7 +1075,9 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         push_op(walker, FZL_OPCODE_LOADCONST);
         push_word(walker, const_n);
 
-        current_res = (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
+        current_res = (fzl_walk_res_t){.type      = FZL_TYPE_NULL,
+                                       .error     = false,
+                                       .classname = node->var.type->value};
         break;
       }
 
@@ -631,11 +1087,20 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         if (rres.error)
           return rres;
 
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_ASSIGN);
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
         if (node->binary_op.left->type == FZL_NODETYPE_DECLARATION)
         {
           fzl_walk_res_t lres = walk(walker, node->binary_op.left);
           if (lres.error)
             return lres;
+
+          push_op(walker, FZL_OPCODE_WRITE);
         }
         else if (node->binary_op.left->type == FZL_NODETYPE_IDENTIFIER)
         {
@@ -649,14 +1114,15 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
 
           if (!found)
           {
-            fzl_token_t *tok = node->binary_op.left->token->value;
+            fzl_token_t *tok = node->binary_op.left->token;
             snprintf(wlast_err, sizeof(wlast_err),
                      "'%s': name '%s' is not exists at %ld:%ld", tok->filename,
                      (char *)tok->value, tok->ln, tok->cn);
             return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
           }
 
-          if (!is_compatible(sym.type, rres.type))
+          if (!is_compatible(sym.type, rres.type, sym.classname,
+                             rres.classname))
           {
             fzl_token_t *tok = node->binary_op.right->token;
             snprintf(wlast_err, sizeof(wlast_err),
@@ -672,10 +1138,67 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
                                         node->binary_op.left->token->value_sz});
           push_op(walker, FZL_OPCODE_LOADCONST);
           push_word(walker, const_n);
+          push_op(walker, FZL_OPCODE_WRITE);
+        }
+        else if (node->binary_op.left->type == FZL_NODETYPE_FIELD)
+        {
+          fzl_node_t *field_node = node->binary_op.left;
+          fzl_walk_res_t obj_res = walk(walker, field_node->memb.parent);
+          if (obj_res.error)
+            return obj_res;
+
+          fzl_ctable_t *ct = NULL;
+          for (size_t i = 0; i < walker->classes_count; i++)
+          {
+            if (strcmp(obj_res.classname, walker->classes[i]->name) == 0)
+            {
+              ct = walker->classes[i];
+              break;
+            }
           }
 
-        push_op(walker, FZL_OPCODE_WRITE);
+          if (!ct)
-        current_res = (fzl_walk_res_t){.type = rres.type, .error = false};
+          {
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "'%s': cannot find class '%s' at %ld:%ld",
+                     field_node->token->filename, obj_res.classname,
+                     field_node->token->ln, field_node->token->cn);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+
+          fzl_ctable_field_t *ctf = NULL;
+          for (size_t i = 0; i < ct->fields_count; i++)
+          {
+            if (strcmp(field_node->memb.field->token->value,
+                       ct->fields[i].name) == 0)
+            {
+              ctf = &ct->fields[i];
+              break;
+            }
+          }
+
+          if (!ctf)
+          {
+            fzl_node_t *fn = field_node->memb.field;
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "'%s': class '%s' has no field '%s' at %ld:%ld",
+                     fn->token->filename, obj_res.classname,
+                     (char *)fn->token->value, fn->token->ln, fn->token->cn);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+
+          push_op(walker, FZL_OPCODE_SET_FIELD);
+          push_word(walker, ctf->slot_index);
+        }
+
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        current_res = (fzl_walk_res_t){
+            .type = rres.type, .error = false, .classname = rres.classname};
         break;
       }
     }
@@ -695,10 +1218,14 @@ int fzl_walk(fzl_walker_t *walker)
     return -1;
   }
 
+  nest_ctx(walker, FZL_WALK_CTX_TYPE_GLOBAL);
+
   push_op(walker, FZL_OPCODE_MK_ENVTABLE);
   fzl_walk_res_t result = walk(walker, walker->root);
   push_op(walker, FZL_OPCODE_RM_ENVTABLE);
 
+  fin_ctx(walker);
+
   if (result.error && !wlast_err[0])
     snprintf(wlast_err, sizeof(wlast_err), "%s", result.error_msg);
 
@@ -722,5 +1249,8 @@ void fzl_freewalker(fzl_walker_t *walker)
   while (walker->sym_top > 0)
     fzl_freesymt(walker->syms[--walker->sym_top]);
 
+  for (size_t i = 0; i < walker->classes_count; i++)
+    fzl_freectable(walker->classes[i]);
+
   free(walker);
 }

src/compiler/main.c

@@ -15,9 +15,15 @@ int main(int argc, char **argv)
 {
   fzl_options_t *opts = fzl_mkoptions(argc, argv);
   if (!opts)
+  {
+    fzl_freeoptions(opts);
     return -1;
+  }
   else if (!opts->should_continue)
+  {
+    fzl_freeoptions(opts);
     return 0;
+  }
 
   if (opts->verbose)
     printf("%s> analyze\n-> reading file...%s", FZL_CDEBUG, FZL_CRST);
@@ -28,6 +34,8 @@ int main(int argc, char **argv)
     char *lasterr = fzl_linked_geterror();
     if (lasterr[0])
       printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, lasterr);
+    fzl_freeoptions(opts);
+    fzl_freelinked(linked);
     return -1;
   }
 
@@ -38,6 +46,8 @@ int main(int argc, char **argv)
     char *lasterr = fzl_linked_geterror();
     if (lasterr[0])
       printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, lasterr);
+    fzl_freeoptions(opts);
+    fzl_freelinked(linked);
     return -1;
   }
 
@@ -53,6 +63,9 @@ int main(int argc, char **argv)
   if (result != 0)
   {
     printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, fzl_reader_geterror());
+    fzl_freeoptions(opts);
+    fzl_freelinked(linked);
+    fzl_freereader(rd);
     return -1;
   }
 
@@ -87,6 +100,10 @@ int main(int argc, char **argv)
   if (result != 0)
   {
     printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, fzl_parser_geterror());
+    fzl_freeoptions(opts);
+    fzl_freeparser(parser);
+    fzl_freereader(rd);
+    fzl_freelinked(linked);
     return -1;
   }
 
@@ -103,6 +120,11 @@ int main(int argc, char **argv)
   if (result != 0)
   {
     printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, fzl_walker_geterror());
+    fzl_freeoptions(opts);
+    fzl_freewalker(walker);
+    fzl_freeparser(parser);
+    fzl_freereader(rd);
+    fzl_freelinked(linked);
     return -1;
   }
 
@@ -144,6 +166,12 @@ int main(int argc, char **argv)
   if (result != 0)
   {
     printf("%sError%s: %s\n", FZL_CERROR, FZL_CRST, fzl_writer_geterror());
+    fzl_freeoptions(opts);
+    fzl_freewriter(writer);
+    fzl_freewalker(walker);
+    fzl_freeparser(parser);
+    fzl_freereader(rd);
+    fzl_freelinked(linked);
     return -1;
   }
 

src/compiler/utils/fzl_const_pool.c

@@ -24,7 +24,7 @@ bool fzl_consts_equal(fzl_const_t a, fzl_const_t b)
   return false;
 }
 
-static uint32_t fzl_hash_const(fzl_const_t c)
+uint32_t fzl_hash_const(fzl_const_t c)
 {
   uint32_t hash       = 2166136261u;
   const uint8_t *data = NULL;
@@ -58,20 +58,20 @@ fzl_const_hash_pool_t *fzl_mkconstpool()
   pool->slots_count    = 0;
   pool->slots_capacity = 16;
   pool->slots = malloc(pool->slots_capacity * sizeof(fzl_const_hash_slot_t));
-  for (int i = 0; i < pool->slots_capacity; i++)
+  for (size_t i = 0; i < pool->slots_capacity; i++)
     pool->slots[i].pool_index = -1;
 
   return pool;
 }
 
-static void fzl_consts_pool_resize_hash(fzl_const_hash_pool_t *pool)
+void fzl_consts_pool_resize_hash(fzl_const_hash_pool_t *pool)
 {
   int old_capacity                 = pool->slots_capacity;
   fzl_const_hash_slot_t *old_slots = pool->slots;
 
   pool->slots_capacity = old_capacity * 2;
   pool->slots = malloc(pool->slots_capacity * sizeof(fzl_const_hash_slot_t));
-  for (int i = 0; i < pool->slots_capacity; i++)
+  for (size_t i = 0; i < pool->slots_capacity; i++)
     pool->slots[i].pool_index = -1;
   pool->slots_count = 0;
 

src/compiler/utils/fzl_ctable.c

@@ -0,0 +1,29 @@
+#include <compiler/utils/fzl_ctable.h>
+#include <stdlib.h>
+#include <string.h>
+
+fzl_ctable_t *fzl_mkctable(char *name)
+{
+  fzl_ctable_t *ctable = malloc(sizeof(fzl_ctable_t));
+  if (!ctable)
+    return NULL;
+
+  memset(ctable, 0, sizeof(fzl_ctable_t));
+  ctable->name             = name;
+  ctable->fields_remainder = 2;
+  ctable->fields =
+      malloc(ctable->fields_remainder * sizeof(fzl_ctable_field_t));
+
+  return ctable;
+}
+
+void fzl_freectable(fzl_ctable_t *ct)
+{
+  if (!ct)
+    return;
+
+  if (ct->fields)
+    free(ct->fields);
+
+  free(ct);
+}

src/compiler/utils/fzl_linked.c

@@ -72,9 +72,9 @@ bool fzl_linked_add_files(fzl_linked_t *l, char **files, size_t files_count)
                              .end   = current_start + file_sz - 1};
 
     if (!l->source)
-      l->source = malloc(file_sz);
+      l->source = malloc(file_sz + 1);
     else
-      l->source = realloc(l->source, current_start + file_sz);
+      l->source = realloc(l->source, current_start + file_sz + 1);
 
     if (!l->source)
     {
@@ -86,6 +86,7 @@ bool fzl_linked_add_files(fzl_linked_t *l, char **files, size_t files_count)
     }
 
     strcpy(l->source + current_start, source);
+    free(source);
     current_start += file_sz;
   }
 

src/compiler/utils/fzl_options.c

@@ -35,7 +35,7 @@ fzl_options_t *fzl_mkoptions(int argc, char **argv)
     return opts;
   }
 
-  size_t i;
+  int i;
   for (i = 1; i < argc; i++)
   {
     if (argv[i][0] != '-')
@@ -108,7 +108,7 @@ fzl_options_t *fzl_mkoptions(int argc, char **argv)
   {
     printf("%sError%s: flags should go before source files list.\n", FZL_CERROR,
            FZL_CRST);
-    printf("Remain %zu arguments are not handled.\n", argc - 1 - i);
+    printf("Remain %d arguments are not handled.\n", argc - 1 - i);
 
     free(files);
     free(opts);

src/compiler/utils/fzl_symtable.c

@@ -1,3 +1,4 @@
+#include <common/fzl_types.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -37,10 +38,31 @@ fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, char *name,
   }
 
   symt->symbols[symt->size++] =
-      (fzl_sym_t){.name = name, .type = type, .ip = ip};
+      (fzl_sym_t){.name = name, .type = type, .ip = ip, .classname = NULL};
   return FZL_SYMTABLE_RESULT_OK;
 }
 
+fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
+                                        char *classname)
+{
+  if (!symt)
+    return FZL_SYMTABLE_RESULT_ERR;
+
+  for (size_t i = 0; i < symt->size; i++)
+  {
+    if (strcmp(symt->symbols[i].name, name) == 0)
+    {
+      if (symt->symbols[i].type != FZL_TYPE_OBJECT)
+        return FZL_SYMTABLE_RESULT_NOT_OBJECT;
+
+      symt->symbols[i].classname = classname;
+      return FZL_SYMTABLE_RESULT_OK;
+    }
+  }
+
+  return FZL_SYMTABLE_RESULT_ERR;
+}
+
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res)
 {
   if (!symt)

src/vm/fzl_vm.c

@@ -1,4 +1,3 @@
-#include "vm/fzl_vm_env.h"
 #include <common/fzl_builtins.h>
 #include <common/fzl_opcodes.h>
 #include <common/fzl_types.h>
@@ -10,6 +9,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <vm/fzl_vm.h>
+#include <vm/fzl_vm_env.h>
+#include <vm/fzl_vm_object.h>
 
 char last_err[256];
 
@@ -41,6 +42,7 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
   if (!fd)
   {
     snprintf(last_err, sizeof(last_err), "failed to open file '%s'", filepath);
+    free(vm);
     return NULL;
   }
 
@@ -49,6 +51,8 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
   if (memcmp(hdr, expect_hdr, 5) != 0)
   {
     snprintf(last_err, sizeof(last_err), "magic check error");
+    fclose(fd);
+    free(vm);
     return NULL;
   }
 
@@ -59,6 +63,8 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
   if (ops_count < 1)
   {
     snprintf(last_err, sizeof(last_err), "there is nothing to do (0 ops)");
+    fclose(fd);
+    free(vm);
     return NULL;
   }
 
@@ -88,6 +94,9 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
       }
       else
       {
+        fclose(fd);
+        free(vm->consts);
+        free(vm);
         snprintf(last_err, sizeof(last_err), "unknown const type at index %ld",
                  i);
         return NULL;
@@ -103,10 +112,167 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
     fread(&op, sizeof(uint64_t), 1, fd);
     vm->ops[i] = op;
   }
+  fclose(fd);
 
   return vm;
 }
 
+// Escape objects with nested objects check
+static void escape_recursive(fzl_vm_env_t *current, fzl_vm_env_t *parent,
+                             fzl_vm_object_t *obj)
+{
+  if (!current || !parent || !obj)
+    return;
+
+  bool found_in_current = false;
+  for (size_t i = 0; i < current->owned_objects_count; i++)
+  {
+    if (current->owned_objects[i] == obj)
+    {
+      current->owned_objects[i] = NULL;
+      found_in_current          = true;
+      break;
+    }
+  }
+
+  if (found_in_current)
+  {
+    bool found_in_parent = false;
+    for (size_t i = 0; i < parent->owned_objects_count; i++)
+    {
+      if (parent->owned_objects[i] == obj)
+      {
+        found_in_parent = true;
+        break;
+      }
+    }
+
+    if (!found_in_parent)
+    {
+      if (parent->owned_objects_remainder <= parent->owned_objects_count)
+      {
+        parent->owned_objects_remainder *= 2;
+        parent->owned_objects =
+            realloc(parent->owned_objects, parent->owned_objects_remainder *
+                                               sizeof(fzl_vm_object_t *));
+      }
+
+      parent->owned_objects[parent->owned_objects_count++] = obj;
+    }
+  }
+
+  for (size_t i = 0; i < obj->values_count; i++)
+  {
+    if (obj->values[i].type == FZL_TYPE_OBJECT && obj->values[i].as.obj != NULL)
+      escape_recursive(current, parent, obj->values[i].as.obj);
+  }
+}
+
+void print_object(fzl_vm_object_t *obj)
+{
+  if (!obj)
+  {
+    printf("<null>\n");
+    return;
+  }
+
+  printf("obj<");
+  for (size_t i = 0; i < obj->values_count; i++)
+  {
+    fzl_value_t arg = obj->values[i];
+
+    if (i > 0)
+      printf(", ");
+
+    if (arg.type == FZL_TYPE_STRING)
+      printf("str(%s)", arg.as.s.value);
+    else if (arg.type == FZL_TYPE_CHAR)
+      printf("char(%c)", arg.as.c);
+    else if (arg.type == FZL_TYPE_INT)
+      printf("int(%ld)", arg.as.i);
+    else if (arg.type == FZL_TYPE_UINT)
+      printf("uint(%lu)", arg.as.u);
+    else if (arg.type == FZL_TYPE_BOOL)
+      printf("bool(%s)", arg.as.b ? "true" : "false");
+    else if (arg.type == FZL_TYPE_NULL)
+      printf("<null>");
+    else if (arg.type == FZL_TYPE_OBJECT)
+      print_object(arg.as.obj);
+    else
+      printf("<unknown>");
+  }
+
+  printf(">\n");
+}
+
+void print_err_data(fzl_vm_t *vm)
+{
+  printf("===== ERROR =====\n");
+  printf("> Caused on IP: %zu\n", vm->ip);
+
+  printf("\n> Data stack:\n");
+  if (vm->dtop > 0)
+  {
+    for (ssize_t i = vm->dtop - 1; i >= 0; i--)
+    {
+      printf("\t> [%d] ", vm->dstack[i].type);
+      switch (vm->dstack[i].type)
+      {
+        case FZL_TYPE_OBJECT:
+          printf("ref: %p\n", vm->dstack[i].as.obj);
+          break;
+        case FZL_TYPE_STRING:
+          printf("str: '%s'\n", vm->dstack[i].as.s.value);
+          break;
+        case FZL_TYPE_NULL:
+          printf("<null>\n");
+          break;
+        default:
+          printf("%lu\n", vm->dstack[i].as.u);
+          break;
+      }
+    }
+  }
+  else
+  {
+    printf("\tEmpty\n");
+  }
+
+  printf("\n> Environments:\n");
+  for (ssize_t i = vm->etop - 1; i >= 0; i--)
+  {
+    fzl_vm_env_t *env = vm->estack[i];
+    printf("\t> [%zd] %p:\n", i, env);
+
+    printf("\t\t> Owned objects (%zu/%zu):\n", env->owned_objects_count,
+           env->owned_objects_remainder);
+    for (size_t j = 0; j < env->owned_objects_count; j++)
+      printf("\t\t\t> ref: %p (entries: %zu)\n", env->owned_objects[j],
+             env->owned_objects[j]->values_count);
+
+    printf("\t\t> Local entries (%zu/%zu):\n", env->size, env->remainder);
+    for (size_t j = 0; j < env->size; j++)
+    {
+      switch (env->table[j].value.type)
+      {
+        case FZL_TYPE_OBJECT:
+          printf("\t\t\t> [%d] %s = ref %p\n", env->table[j].value.type,
+                 env->table[j].name, env->table[j].value.as.obj);
+          break;
+
+        default:
+          printf("\t\t\t> [%d] %s = %lu\n", env->table[j].value.type,
+                 env->table[j].name, env->table[j].value.as.u);
+          break;
+      }
+    }
+  }
+
+  printf("\n> Call stack:\n");
+  for (ssize_t i = vm->ctop - 1; i >= 0; i--)
+    printf("\t> [%zd] %lu\n", i, vm->cstack[i]);
+}
+
 int fzl_vm_run(fzl_vm_t *vm)
 {
   if (!vm)
@@ -122,6 +288,235 @@ int fzl_vm_run(fzl_vm_t *vm)
 
     switch (opcode)
     {
+      case FZL_OPCODE_DEREFERENCE:
+      {
+        if (vm->dtop < 1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected value in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_value_t addr = vm->dstack[--vm->dtop];
+        if (addr.type < FZL_TYPE_INT8)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected address");
+          print_err_data(vm);
+          return -1;
+        }
+
+        if (addr.as.u == 0)
+        {
+          vm->dstack[vm->dtop++] =
+              (fzl_value_t){.type = FZL_TYPE_OBJECT, .as.obj = NULL};
+          break;
+        }
+
+        vm->dstack[vm->dtop++] = (fzl_value_t){
+            .type = FZL_TYPE_OBJECT, .as.obj = (fzl_vm_object_t *)addr.as.u};
+        break;
+      }
+
+      case FZL_OPCODE_CMP_EQ_STR:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+        fzl_value_t left  = vm->dstack[--vm->dtop];
+        fzl_value_t right = vm->dstack[--vm->dtop];
+
+        int result = strcmp(left.as.s.value, right.as.s.value);
+        vm->dstack[vm->dtop++] =
+            (fzl_value_t){.type = FZL_TYPE_BOOL, .as.b = result == 0};
+        break;
+      }
+
+      case FZL_OPCODE_CMP_NEQ_STR:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+        fzl_value_t left  = vm->dstack[--vm->dtop];
+        fzl_value_t right = vm->dstack[--vm->dtop];
+
+        int result = strcmp(left.as.s.value, right.as.s.value);
+        vm->dstack[vm->dtop++] =
+            (fzl_value_t){.type = FZL_TYPE_BOOL, .as.b = result != 0};
+        break;
+      }
+
+      case FZL_OPCODE_CMP_EQ_OBJ:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+        fzl_value_t left  = vm->dstack[--vm->dtop];
+        fzl_value_t right = vm->dstack[--vm->dtop];
+
+        vm->dstack[vm->dtop++] = (fzl_value_t){
+            .type = FZL_TYPE_BOOL, .as.b = left.as.obj == right.as.obj};
+        break;
+      }
+
+      case FZL_OPCODE_CMP_NEQ_OBJ:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+        fzl_value_t left  = vm->dstack[--vm->dtop];
+        fzl_value_t right = vm->dstack[--vm->dtop];
+
+        vm->dstack[vm->dtop++] = (fzl_value_t){
+            .type = FZL_TYPE_BOOL, .as.b = left.as.obj != right.as.obj};
+        break;
+      }
+
+      case FZL_OPCODE_ESCAPE_OBJECT:
+      {
+        if (vm->dtop < 1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - missing value in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+        fzl_value_t obj = vm->dstack[--vm->dtop];
+        if (obj.type != FZL_TYPE_OBJECT)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot escape non-object type");
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_vm_env_t *parent  = vm->estack[vm->etop - 2];
+        fzl_vm_env_t *current = vm->estack[vm->etop - 1];
+        if (vm->etop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot escape object from global env");
+          print_err_data(vm);
+          return -1;
+        }
+
+        escape_recursive(current, parent, obj.as.obj);
+        vm->dstack[vm->dtop++] = obj;
+
+        break;
+      }
+
+      case FZL_OPCODE_ALLOC_OBJECT:
+      {
+        uint64_t values_count = vm->ops[++vm->ip];
+        fzl_vm_object_t *obj  = malloc(sizeof(fzl_vm_object_t));
+        obj->values           = malloc(values_count * sizeof(fzl_value_t));
+        obj->values_count     = values_count;
+
+        fzl_vm_env_t *current_env = vm->estack[vm->etop - 1];
+        if (current_env->owned_objects_remainder <=
+            current_env->owned_objects_count)
+        {
+          current_env->owned_objects_remainder *= 2;
+          current_env->owned_objects = realloc(
+              current_env->owned_objects,
+              current_env->owned_objects_remainder * sizeof(fzl_vm_object_t *));
+        }
+
+        current_env->owned_objects[current_env->owned_objects_count++] = obj;
+        vm->dstack[vm->dtop++] =
+            (fzl_value_t){.type = FZL_TYPE_OBJECT, .as.obj = obj};
+        break;
+      }
+
+      case FZL_OPCODE_GET_FIELD:
+      {
+        if (vm->dtop < 1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected value in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+
+        uint64_t field_slot = vm->ops[++vm->ip];
+        fzl_value_t val     = vm->dstack[--vm->dtop];
+        if (val.type != FZL_TYPE_OBJECT)
+        {
+          snprintf(
+              last_err, sizeof(last_err),
+              "runtime error - cannot access field #%lu of non-object type",
+              field_slot);
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_vm_object_t *obj = val.as.obj;
+        if (obj->values_count <= field_slot)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot access field #%lu", field_slot);
+          print_err_data(vm);
+          return -1;
+        }
+
+        vm->dstack[vm->dtop++] = obj->values[field_slot];
+        break;
+      }
+
+      case FZL_OPCODE_SET_FIELD:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          print_err_data(vm);
+          return -1;
+        }
+
+        uint64_t field_slot = vm->ops[++vm->ip];
+        fzl_value_t objval  = vm->dstack[--vm->dtop];
+        fzl_value_t wrval   = vm->dstack[--vm->dtop];
+        if (objval.type != FZL_TYPE_OBJECT)
+        {
+          snprintf(
+              last_err, sizeof(last_err),
+              "runtime error - cannot access field #%lu of non-object type",
+              field_slot);
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_vm_object_t *obj = objval.as.obj;
+        if (obj->values_count <= field_slot)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot access field #%lu", field_slot);
+          print_err_data(vm);
+          return -1;
+        }
+
+        obj->values[field_slot] = wrval;
+        break;
+      }
+
       case FZL_OPCODE_CALL:
       {
         uint64_t ip            = vm->ops[++vm->ip];
@@ -136,6 +531,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - no place to jump");
+          print_err_data(vm);
           return -1;
         }
 
@@ -148,6 +544,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -162,6 +559,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -176,6 +574,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -190,6 +589,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -204,6 +604,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -218,6 +619,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -232,6 +634,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected value in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -245,6 +648,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected value in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -255,14 +659,24 @@ int fzl_vm_run(fzl_vm_t *vm)
         break;
 
       case FZL_OPCODE_JMP:
-        vm->ip = vm->ops[++vm->ip] - 1;
+      {
+        if (vm->ops_count <= vm->ip)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected JMP addr");
+          return -1;
+        }
+        uint64_t jmp_ip = vm->ops[++vm->ip];
+        vm->ip          = jmp_ip - 1;
         break;
+      }
 
       case FZL_OPCODE_AND:
         if (vm->dtop < 2)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -277,6 +691,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected two values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -291,6 +706,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected var name in data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -305,14 +721,36 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in data stack");
+          print_err_data(vm);
           return -1;
         }
 
         fzl_value_t writevar = vm->dstack[--vm->dtop];
         fzl_value_t value    = vm->dstack[--vm->dtop];
 
-        fzl_vm_env_wresult_t wresult = fzl_env_writevalue(
+        char *wrname = (char *)writevar.as.s.value;
-            vm->estack[vm->etop - 1], (char *)writevar.as.s.value, value);
+        bool wrfound;
+        fzl_value_t wrenv;
+        ssize_t wrlvl = -1;
+        for (ssize_t i = vm->etop - 1; i >= 0; i--)
+        {
+          if ((wrfound = fzl_env_lookup(vm->estack[i], wrname, &wrenv)))
+          {
+            wrlvl = i;
+            break;
+          }
+        }
+
+        if (wrlvl <= -1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - name '%s' not found in this scope", wrname);
+          print_err_data(vm);
+          return -1;
+        }
+
+        fzl_vm_env_wresult_t wresult =
+            fzl_env_writevalue(vm->estack[wrlvl], (char *)wrname, value);
         if (wresult != FZL_VM_ENV_WRESULT_OK)
         {
           switch (wresult)
@@ -320,21 +758,25 @@ int fzl_vm_run(fzl_vm_t *vm)
             case FZL_VM_ENV_WRESULT_ERR:
               snprintf(last_err, sizeof(last_err),
                        "runtime error - failed to write variable");
+              print_err_data(vm);
               return -1;
 
             case FZL_VM_ENV_WRESULT_ERR_EXISTS:
               snprintf(last_err, sizeof(last_err),
                        "runtime error - redefenition of '%s'",
                        writevar.as.s.value);
+              print_err_data(vm);
               return -1;
 
             case FZL_VM_ENV_WRESULT_ERR_NOT_FOUND:
               snprintf(last_err, sizeof(last_err),
                        "runtime error - cannot find name '%s'",
                        writevar.as.s.value);
+              print_err_data(vm);
               return -1;
 
             default:
+              print_err_data(vm);
               return -1;
           }
         }
@@ -358,6 +800,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - LOOKUP_ENV: empty data stack");
+          print_err_data(vm);
           return -1;
         }
 
@@ -390,14 +833,22 @@ int fzl_vm_run(fzl_vm_t *vm)
           else if (arg.type == FZL_TYPE_UINT)
             printf("%lu\n", arg.as.u);
           else if (arg.type == FZL_TYPE_BOOL)
-            printf("%b\n", arg.as.b);
+            printf("%s\n", arg.as.b ? "true" : "false");
           else if (arg.type == FZL_TYPE_NULL)
             printf("<null>\n");
+          else if (arg.type == FZL_TYPE_OBJECT)
+            print_object(arg.as.obj);
+        }
+        else if (fn_id == FZL_BUILTIN_EXIT)
+        {
+          fzl_value_t arg = vm->dstack[--vm->dtop];
+          return arg.as.i;
         }
         else
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - undefined builtin %lu", fn_id);
+          print_err_data(vm);
           return -1;
         }
       }
@@ -409,6 +860,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         if (vm->consts_count <= cn)
         {
           snprintf(last_err, sizeof(last_err), "runtime error - unknown const");
+          print_err_data(vm);
           return -1;
         }
         fzl_const_t c = vm->consts[cn];
@@ -424,6 +876,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t add1 = vm->dstack[--vm->dtop];
@@ -437,6 +890,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t sub2 = vm->dstack[--vm->dtop];
@@ -450,6 +904,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t mul1 = vm->dstack[--vm->dtop];
@@ -463,6 +918,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t div1 = vm->dstack[--vm->dtop];
@@ -476,6 +932,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t pow2 = vm->dstack[--vm->dtop];
@@ -496,6 +953,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected 2 values in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t mod1 = vm->dstack[--vm->dtop];
@@ -509,6 +967,7 @@ int fzl_vm_run(fzl_vm_t *vm)
         {
           snprintf(last_err, sizeof(last_err),
                    "runtime error - expected value in stack");
+          print_err_data(vm);
           return -1;
         }
         fzl_value_t neg_n = vm->dstack[--vm->dtop];
@@ -535,6 +994,7 @@ int fzl_vm_run(fzl_vm_t *vm)
       default:
         snprintf(last_err, sizeof(last_err),
                  "runtime error - unknown opcode %u", opcode);
+        print_err_data(vm);
         return -1;
     }
 
@@ -551,6 +1011,9 @@ void fzl_freevm(fzl_vm_t *vm)
   if (!vm)
     return;
 
+  while (vm->etop > 0)
+    fzl_freeenv(vm->estack[--vm->etop]);
+
   for (size_t i = 0; i < vm->consts_count; i++)
   {
     if (vm->consts[i].type == FZL_CONSTTYPE_STRING)

src/vm/fzl_vm_debug.c

@@ -20,15 +20,51 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
 
     switch (vm->ops[i])
     {
+      case FZL_OPCODE_DEREFERENCE:
+        printf("DEREFERENCE\n");
+        break;
+
+      case FZL_OPCODE_CMP_EQ_STR:
+        printf("CMP_EQ_STR\n");
+        break;
+
+      case FZL_OPCODE_CMP_NEQ_STR:
+        printf("CMP_NEQ_STR\n");
+        break;
+
+      case FZL_OPCODE_CMP_EQ_OBJ:
+        printf("CMP_EQ_OBJ\n");
+        break;
+
+      case FZL_OPCODE_CMP_NEQ_OBJ:
+        printf("CMP_NEQ_OBJ\n");
+        break;
+
+      case FZL_OPCODE_ESCAPE_OBJECT:
+        printf("ESCAPE_OBJ\n");
+        break;
+
+      case FZL_OPCODE_ALLOC_OBJECT:
+        printf("ALLOC_OBJECT: %lu fields\n", vm->ops[++i]);
+        break;
+
+      case FZL_OPCODE_GET_FIELD:
+        printf("GET_FIELD #%lu\n", vm->ops[++i]);
+        break;
+
+      case FZL_OPCODE_SET_FIELD:
+        printf("SET_FIELD #%lu\n", vm->ops[++i]);
+        break;
+
       case FZL_OPCODE_CALL:
       {
         size_t ip = vm->ops[++i];
-        printf("Call IP: %lu\n", ip);
+        printf("CALL IP: %lu\n", ip);
         break;
       }
 
       case FZL_OPCODE_RET:
-        printf("Return\n");
+        printf("RET\n");
         break;
 
       case FZL_OPCODE_LOADCONST:
@@ -77,7 +113,7 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
       case FZL_OPCODE_DIV:
       case FZL_OPCODE_POW:
       case FZL_OPCODE_MOD:
-        printf("Math opcode\n");
+        printf("MATH\n");
         break;
 
       case FZL_OPCODE_AND:
@@ -129,7 +165,7 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
         break;
 
       default:
-        printf("<Unknown>\n");
+        printf("<UNKNOWN>\n");
     }
   }
 }

src/vm/fzl_vm_env.c

@@ -1,3 +1,4 @@
+#include "vm/fzl_vm_object.h"
 #include <common/fzl_types.h>
 #include <common/fzl_value.h>
 #include <stdbool.h>
@@ -6,8 +7,6 @@
 #include <string.h>
 #include <vm/fzl_vm_env.h>
 
-static const fzl_value_t null = {.type = FZL_TYPE_NULL};
-
 fzl_vm_env_t *fzl_mkenv()
 {
   fzl_vm_env_t *env = malloc(sizeof(fzl_vm_env_t));
@@ -15,6 +14,11 @@ fzl_vm_env_t *fzl_mkenv()
   env->size         = 0;
   env->table        = malloc(env->remainder * sizeof(fzl_vm_env_entry_t));
 
+  env->owned_objects_remainder = 2;
+  env->owned_objects_count     = 0;
+  env->owned_objects =
+      malloc(env->owned_objects_remainder * sizeof(fzl_vm_object_t *));
+
   return env;
 }
 
@@ -96,5 +100,21 @@ void fzl_freeenv(fzl_vm_env_t *env)
   if (env->table)
     free(env->table);
 
+  if (env->owned_objects)
+  {
+    for (size_t i = 0; i < env->owned_objects_count; i++)
+    {
+      if (!env->owned_objects[i])
+        continue;
+
+      if (env->owned_objects[i]->values)
+        free(env->owned_objects[i]->values);
+
+      free(env->owned_objects[i]);
+    }
+
+    free(env->owned_objects);
+  }
+
   free(env);
 }

src/vm/main.c

@@ -33,7 +33,7 @@ run_args_t *parse_args(int argc, char **argv)
   args->help       = false;
   args->debug      = false;
 
-  for (size_t i = 0; i < argc; i++)
+  for (int i = 0; i < argc; i++)
   {
     if (argv[i][0] != '-')
       continue;
@@ -49,6 +49,7 @@ run_args_t *parse_args(int argc, char **argv)
     {
       printf("Error: unknown flag '%s'.\n", argv[i]);
       printf("Use 'fz --help' to read the usage\n");
+      free(args);
       return NULL;
     }
   }
@@ -57,6 +58,7 @@ run_args_t *parse_args(int argc, char **argv)
   {
     printf("Error: last argument MUST be a file path\n");
     printf("Use 'fz --help' for help\n");
+    free(args);
     return NULL;
   }
 
@@ -73,6 +75,7 @@ int main(int argc, char **argv)
   else if (args->help)
   {
     print_hint();
+    free(args);
     return 0;
   }
 
@@ -80,6 +83,7 @@ int main(int argc, char **argv)
   if (!vm)
   {
     printf("Error: %s\n", fzl_vm_geterror());
+    free(args);
     return -1;
   }
 
@@ -90,7 +94,12 @@ int main(int argc, char **argv)
     int result = fzl_vm_run(vm);
     if (result != 0)
     {
-      printf("Error: %s\n", fzl_vm_geterror());
+      char *err = fzl_vm_geterror();
+      if (err && err[0])
+        printf("Error: %s\n", err);
+
+      free(args);
+      fzl_freevm(vm);
       return -1;
     }
   }