diff --git a/Makefile b/Makefile
index 6dfb306..1f3c1dd 100644
--- a/Makefile
+++ b/Makefile
@@ -7,13 +7,16 @@ build:
 tests: build
 	build/roza-tests
 
-install: build
+install: tests
 	meson install -C build
 
 check:
 	@cppcheck --language=c --enable=all lib src -q \
-	--suppress=missingIncludeSystem
+	--suppress=missingIncludeSystem \
+	--suppress=missingInclude \
+	--suppress=unmatchedSuppression
 
 	@cppcheck --language=c --enable=all tests/units -q \
 	--suppress=missingIncludeSystem \
-	--suppress=unusedFunction
+	--suppress=unusedFunction \
+	--suppress=unmatchedSuppression
diff --git a/doc/roza.bnf b/doc/roza.bnf
index e69de29..6e3027d 100644
--- a/doc/roza.bnf
+++ b/doc/roza.bnf
@@ -0,0 +1,2 @@
+MOD ::= EXPR*
+EXPR ::= num
diff --git a/lib/commons.h b/lib/commons.h
new file mode 100644
index 0000000..61f0193
--- /dev/null
+++ b/lib/commons.h
@@ -0,0 +1,30 @@
+#ifndef RZ_COMMONS_H
+#define RZ_COMMONS_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include <ctype.h>
+
+#include <conf.h>
+#include "str.h"
+
+#define RZ_STR_LIMIT 256
+#define RZ_STACK_LIMIT 1024
+#define RZ_MAX_TYPES 256
+
+#define RZ_NO_PARAM (-1)
+typedef int param_t;
+
+#define RZ_ENUM_ID(X) X
+#define RZ_ENUM_STR(X) #X
+
+#define RZ_ENUM_H(PREFIX, NAME)                         \
+  typedef enum PREFIX { NAME(RZ_ENUM_ID) } PREFIX;      \
+  extern char const* PREFIX ## Str []
+
+#define RZ_ENUM_C(PREFIX, NAME)                         \
+  char const* PREFIX ## Str [] = { NAME(RZ_ENUM_STR) }
+
+#endif
diff --git a/lib/compiler.c b/lib/compiler.c
new file mode 100644
index 0000000..7b4335e
--- /dev/null
+++ b/lib/compiler.c
@@ -0,0 +1,50 @@
+#include "compiler.h"
+#include "lib/commons.h"
+
+void compiler_init(compiler_t* compiler, mod_t* mod, tysy_t* tysy, err_t* err)
+{
+  assert(compiler);
+  assert(err);
+
+  compiler->mod = mod;
+  compiler->tysy = tysy;
+  compiler->err = err;
+}
+
+void compiler_free(compiler_t* compiler)
+{
+  assert(compiler);
+}
+
+void compiler_run(compiler_t* compiler, node_t* node)
+{
+  assert(compiler);
+  assert(node);
+
+  switch (node->type)
+    {
+    case NODE_MOD: {
+      for (size_t i=0; i<node->children.size; i++)
+        {
+          compiler_run(compiler, (node_t*) node->children.data[i]);
+        }
+    } break;
+
+    case NODE_NUM: {
+      double value = atof(node->value.data);
+      value_t* val = tysy_new_num(compiler->tysy, value);
+      Opcode op = OP_PUSH;
+      param_t param = (param_t) mod_push_new_value(compiler->mod, val);
+
+      mod_push_instr(compiler->mod, op, param);
+
+    } break;
+
+    default: {
+      char msg[RZ_STR_LIMIT];
+      snprintf(msg, RZ_STR_LIMIT, "Unknown node '%s'",
+               NodeTypeStr[node->type]);
+      err_error(compiler->err, msg, node->line);
+    } break;
+    }
+}
diff --git a/lib/compiler.h b/lib/compiler.h
new file mode 100644
index 0000000..5cf2652
--- /dev/null
+++ b/lib/compiler.h
@@ -0,0 +1,21 @@
+#ifndef RZ_COMPILER_H
+#define RZ_COMPILER_H
+
+#include "commons.h"
+#include "err.h"
+#include "mod.h"
+#include "node.h"
+#include "tysy.h"
+
+typedef struct {
+  mod_t* mod;
+  tysy_t* tysy;
+  err_t* err;
+} compiler_t;
+
+void compiler_init(compiler_t* compiler, mod_t* mod, tysy_t* tysy, err_t* err);
+void compiler_free(compiler_t* compiler);
+
+void compiler_run(compiler_t* compiler, node_t* node);
+
+#endif
diff --git a/lib/err.c b/lib/err.c
new file mode 100644
index 0000000..9d3eb6e
--- /dev/null
+++ b/lib/err.c
@@ -0,0 +1,47 @@
+#include "err.h"
+
+void err_init(err_t* err)
+{
+  assert(err);
+  err->size = 0;
+}
+
+void err_free(err_t* err)
+{
+  assert(err);
+
+  for (size_t i=0; i<err->size; i++)
+    {
+      free(err->errors[i]->what);
+      free(err->errors[i]);
+    }
+
+  err->size = 0;
+}
+
+void err_error(err_t* err, char* what, int line)
+{
+  assert(err);
+  assert(err->size + 1 < RZ_ERROR_STACK_SIZE);
+
+  err->errors[err->size] = malloc(sizeof(err_msg_t));
+  err->errors[err->size]->what = strdup(what);
+  err->errors[err->size]->line = line;
+  err->size++;
+}
+
+void err_abort(err_t* err)
+{
+  assert(err);
+
+  for (size_t i=0; i<err->size; i++)
+    {
+      fprintf(stderr, "ERR(%d) %s\n",
+              err->errors[i]->line,
+              err->errors[i]->what);
+    }
+
+  err_free(err);
+
+  abort();
+}
diff --git a/lib/err.h b/lib/err.h
new file mode 100644
index 0000000..09d2c4f
--- /dev/null
+++ b/lib/err.h
@@ -0,0 +1,24 @@
+#ifndef RZ_ERR_H
+#define RZ_ERR_H
+
+#define RZ_ERROR_STACK_SIZE 256
+
+#include "commons.h"
+
+typedef struct {
+  char* what;
+  int line;
+} err_msg_t;
+
+typedef struct {
+  size_t size;
+  err_msg_t* errors[RZ_ERROR_STACK_SIZE];
+} err_t;
+
+void err_init(err_t* err);
+void err_free(err_t* err);
+
+void err_error(err_t* err, char* what, int line);
+void err_abort(err_t* err);
+
+#endif
diff --git a/lib/lexer.c b/lib/lexer.c
new file mode 100644
index 0000000..2ed9c6f
--- /dev/null
+++ b/lib/lexer.c
@@ -0,0 +1,95 @@
+#include "lexer.h"
+#include "lib/commons.h"
+
+void lexer_init(lexer_t* lexer, char const* source, err_t* err)
+{
+  assert(lexer);
+  lexer->source = strdup(source);
+  lexer->cursor = 0;
+  lexer->err = err;
+  lexer->line = 1;
+}
+
+void lexer_free(lexer_t* lexer)
+{
+  assert(lexer);
+  free(lexer->source);
+  lexer->source = NULL;
+}
+
+node_t* lexer_try_new_next(lexer_t* lexer)
+{
+  assert(lexer);
+  size_t len = strlen(lexer->source);
+
+  // skip spaces
+  {
+    while (lexer->cursor < len
+           && isspace(lexer->source[lexer->cursor]))
+      {
+        if (lexer->source[lexer->cursor] == '\n')
+          {
+            lexer->line++;
+          }
+
+        lexer->cursor++;
+      }
+  }
+
+  // scan num
+  {
+    size_t cursor = lexer->cursor;
+
+    str_t res_str;
+    str_init(&res_str);
+
+    if (cursor < len && lexer->source[cursor] == '-')
+      {
+        str_push(&res_str, lexer->source[cursor]);
+        cursor++;
+      }
+
+    while (cursor < len
+           && isdigit(lexer->source[cursor]))
+      {
+        str_push(&res_str, lexer->source[cursor]);
+        cursor += 1;
+      }
+
+    if (cursor < len && lexer->source[cursor] == '.')
+      {
+        str_push(&res_str, lexer->source[cursor]);
+        cursor++;
+
+        while (cursor < len
+               && isdigit(lexer->source[cursor]))
+          {
+            str_push(&res_str, lexer->source[cursor]);
+            cursor += 1;
+          }
+      }
+
+    if (res_str.size > 0
+        && (cursor >= len || isspace(lexer->source[cursor])))
+      {
+        node_t* tok = malloc(sizeof(node_t));
+        node_init(tok, NODE_NUM, res_str.data, lexer->line);
+        str_free(&res_str);
+
+        lexer->cursor = cursor;
+        return tok;
+      }
+
+    str_free(&res_str);
+  }
+
+  if (lexer->cursor < len && lexer->err)
+    {
+      size_t const SZ = RZ_STR_LIMIT;
+      char msg[SZ];
+      snprintf(msg, SZ, "unexpected symbol '%c'", lexer->source[lexer->cursor]);
+      err_error(lexer->err, msg, lexer->line);
+    }
+
+  return NULL;
+}
diff --git a/lib/lexer.h b/lib/lexer.h
new file mode 100644
index 0000000..179cce6
--- /dev/null
+++ b/lib/lexer.h
@@ -0,0 +1,20 @@
+#ifndef RZ_LEXER_H
+#define RZ_LEXER_H
+
+#include "commons.h"
+#include "node.h"
+#include "err.h"
+
+typedef struct {
+  err_t* err;
+  char* source;
+  size_t cursor;
+  int line;
+} lexer_t;
+
+void lexer_init(lexer_t* lexer, char const* source, err_t* err);
+void lexer_free(lexer_t* lexer);
+
+node_t* lexer_try_new_next(lexer_t* lexer);
+
+#endif
diff --git a/lib/loader.c b/lib/loader.c
new file mode 100644
index 0000000..a5109a5
--- /dev/null
+++ b/lib/loader.c
@@ -0,0 +1,124 @@
+#include "lexer.h"
+#include "parser.h"
+#include "loader.h"
+#include "compiler.h"
+#include "mod.h"
+#include "vm.h"
+
+void loader_init(loader_t* loader)
+{
+  assert(loader);
+}
+
+void loader_free(loader_t* loader)
+{
+  assert(loader);
+}
+
+void loader_ldfile(loader_t* loader, char const* path, int debug)
+{
+  assert(loader);
+  str_t source;
+  str_init(&source);
+
+  // read sources
+  {
+    FILE* file = fopen(path, "r");
+
+    if (!file)
+      {
+        fprintf(stderr, "Cannot open file '%s'.\n", path);
+        abort();
+      }
+
+    char buf;
+    size_t sz;
+
+    while ( (sz = fread(&buf, sizeof(char), 1, file)) )
+      {
+        str_push(&source, buf);
+      }
+
+    fclose(file);
+  }
+
+  if (str_empty(&source))
+    {
+      str_free(&source);
+      return;
+    }
+
+  tysy_t tysy;
+  tysy_init(&tysy);
+
+  err_t err;
+  err_init(&err);
+
+  lexer_t lex;
+  lexer_init(&lex, source.data, &err);
+
+  parser_t parser;
+  parser_init(&parser, &lex, &err);
+
+  node_t* node = parser_try_new_tree(&parser);
+
+  if (node)
+    {
+      mod_t mod;
+      mod_init(&mod);
+
+      // compile
+      {
+        compiler_t compiler;
+        compiler_init(&compiler, &mod, &tysy, &err);
+        compiler_run(&compiler, node);
+        compiler_free(&compiler);
+        node_free(node);
+        free(node);
+      }
+
+      // execute
+      {
+        vm_t vm;
+        vm_init(&vm);
+
+        vm_exec_mod(&vm, &mod);
+
+        if (debug)
+          {
+            {
+              char msg[RZ_STR_LIMIT];
+              mod_str(&mod, msg, RZ_STR_LIMIT);
+              printf("%s", msg);
+            }
+
+            {
+              char msg[RZ_STR_LIMIT];
+              vm_stack_str(&vm, msg, RZ_STR_LIMIT);
+              printf("\n======== STACK ========\n");
+              printf("%s\n", msg);
+            }
+          }
+
+        vm_free(&vm);
+      }
+
+      mod_free(&mod);
+    }
+
+  // free
+  parser_free(&parser);
+  lexer_free(&lex);
+  str_free(&source);
+
+  if (err.size > 0)
+    {
+      err_abort(&err);
+    }
+  else
+    {
+      err_free(&err);
+    }
+
+  tysy_free(&tysy);
+}
diff --git a/lib/loader.h b/lib/loader.h
new file mode 100644
index 0000000..91f39f7
--- /dev/null
+++ b/lib/loader.h
@@ -0,0 +1,15 @@
+#ifndef RZ_LOADER_H
+#define RZ_LOADER_H
+
+#include "commons.h"
+
+typedef struct {
+
+} loader_t;
+
+void loader_init(loader_t* loader);
+void loader_free(loader_t* loader);
+
+void loader_ldfile(loader_t* loader, char const* path, int debug);
+
+#endif
diff --git a/lib/mod.c b/lib/mod.c
new file mode 100644
index 0000000..9f5ca93
--- /dev/null
+++ b/lib/mod.c
@@ -0,0 +1,118 @@
+#include "mod.h"
+
+void mod_init(mod_t* mod)
+{
+  assert(mod);
+
+  mod->program.size = 0;
+  mod->program.cap = 0;
+  mod->program.ops = NULL;
+  mod->program.params = NULL;
+
+  mod->values.size = 0;
+  mod->values.cap = 0;
+  mod->values.data = NULL;
+}
+
+void mod_free(mod_t* mod)
+{
+  assert(mod);
+  free(mod->program.ops);
+  free(mod->program.params);
+  mod->program.size = 0;
+  mod->program.cap = 0;
+
+  for (size_t i=0; i<mod->values.size; i++)
+    {
+      value_free(mod->values.data[i]);
+      free(mod->values.data[i]);
+    }
+
+  free(mod->values.data);
+  mod->values.data = NULL;
+  mod->values.size = 0;
+  mod->values.cap = 0;
+}
+
+void mod_push_instr(mod_t* mod, Opcode op, param_t param)
+{
+  assert(mod);
+
+  if (mod->program.cap == 0)
+    {
+      mod->program.cap = 2;
+      mod->program.ops = malloc(sizeof(Opcode) * mod->program.cap);
+      mod->program.params = malloc(sizeof(param_t) * mod->program.cap);
+    }
+
+  if (mod->program.size >= mod->program.cap)
+    {
+      mod->program.cap *= 2;
+      mod->program.ops = realloc(mod->program.ops,
+                                 sizeof(Opcode) * mod->program.cap);
+      mod->program.params = realloc(mod->program.params,
+                                    sizeof(param_t) * mod->program.cap);
+    }
+
+  mod->program.ops[mod->program.size] = op;
+  mod->program.params[mod->program.size] = param;
+  mod->program.size++;
+}
+
+size_t mod_str(mod_t* mod, char* buffer, size_t size)
+{
+  size_t sz = 0;
+
+  sz += snprintf(buffer + sz, size - sz, "======== VALUES ========\n");
+  for (size_t i=0; i<mod->values.size; i++)
+    {
+      sz += snprintf(buffer + sz, size - sz, "%d| ", (int) i);
+      sz += value_str(mod->values.data[i], buffer + sz, size - sz);
+      sz += snprintf(buffer + sz, size - sz, "\n");
+    }
+
+  sz += snprintf(buffer + sz, size - sz, "\n======== PROGRAM ========\n");
+  for (size_t i=0; i<mod->program.size; i++)
+    {
+      sz += snprintf(buffer + sz, size - sz, "%d| %s %d\n",
+                     (int) i,
+                     OpcodeStr[mod->program.ops[i]] + strlen("OP_"),
+                     mod->program.params[i]);
+    }
+
+  return sz;
+}
+
+size_t mod_push_new_value(mod_t* mod, value_t* value)
+{
+  assert(mod);
+  assert(value);
+
+  for (size_t i=0; i<mod->values.size; i++)
+    {
+      if (value_eq(value, mod->values.data[i]))
+        {
+          value_free(value);
+          free(value);
+          return i;
+        }
+    }
+
+  if (mod->values.size == 0)
+    {
+      mod->values.cap = 2;
+      mod->values.data = malloc(sizeof(value_t*) * mod->values.cap);
+    }
+
+  if (mod->values.size >= mod->values.cap)
+    {
+      mod->values.cap *= 2;
+      mod->values.data = realloc(mod->values.data,
+                                 sizeof(value_t*) * mod->values.cap);
+    }
+
+  mod->values.data[mod->values.size] = value;
+  mod->values.size++;
+
+  return mod->values.size - 1;
+}
diff --git a/lib/mod.h b/lib/mod.h
new file mode 100644
index 0000000..1af1ab7
--- /dev/null
+++ b/lib/mod.h
@@ -0,0 +1,31 @@
+#ifndef RZ_MOD_H
+#define RZ_MOD_H
+
+#include "commons.h"
+#include "opcodes.h"
+#include "value.h"
+
+typedef struct {
+  struct {
+    size_t size;
+    size_t cap;
+    Opcode* ops;
+    param_t* params;
+  } program;
+
+  struct {
+    size_t size;
+    size_t cap;
+    value_t** data;
+  } values;
+} mod_t;
+
+void mod_init(mod_t* mod);
+void mod_free(mod_t* mod);
+
+void mod_push_instr(mod_t* mod, Opcode op, param_t param);
+size_t mod_str(mod_t* mod, char* buffer, size_t size);
+
+size_t mod_push_new_value(mod_t* mod, value_t* value);
+
+#endif
diff --git a/lib/node.c b/lib/node.c
new file mode 100644
index 0000000..f186cdc
--- /dev/null
+++ b/lib/node.c
@@ -0,0 +1,91 @@
+#include "node.h"
+
+RZ_ENUM_C(NodeType, NODE_TYPE);
+
+void node_init(node_t* node, NodeType type, char* value, int line)
+{
+  assert(node);
+  assert(value);
+
+  node->type = type;
+  str_init(&node->value);
+  str_append(&node->value, value);
+
+  node->line = line;
+
+  node->children.size = 0;
+  node->children.cap = 0;
+  node->children.data = NULL;
+}
+
+void node_free(node_t* node)
+{
+  assert(node);
+  str_free(&node->value);
+
+  for (size_t i=0; i<node->children.size; i++)
+    {
+      node_free((node_t*) node->children.data[i]);
+      free(node->children.data[i]);
+    }
+
+  free(node->children.data);
+  node->children.size = 0;
+  node->children.cap = 0;
+}
+
+void node_add_child(node_t* node, node_t* child)
+{
+  assert(node);
+  assert(child);
+
+  if (node->children.cap == 0)
+    {
+      node->children.cap = 2;
+      node->children.data = malloc(sizeof(node_t) * node->children.cap);
+    }
+
+  if (node->children.size >= node->children.cap)
+    {
+      node->children.cap *= 2;
+      node->children.data = realloc(node->children.data,
+                                    sizeof(node_t) * node->children.cap);
+    }
+
+  size_t sz = node->children.size;
+  node->children.data[sz] = (struct node_t*) child;
+  node->children.size++;
+}
+
+size_t node_str(node_t* node, char* buffer, size_t size)
+{
+  assert(node);
+  size_t sz = 0;
+
+  sz += snprintf(buffer + sz, size - sz, "%s",
+                 NodeTypeStr[node->type] + strlen("NODE_"));
+
+  if (!str_empty(&node->value))
+    {
+      sz += snprintf(buffer + sz, size - sz, "[%s]", node->value.data);
+    }
+
+  if (node->children.size > 0)
+    {
+      sz += snprintf(buffer +sz, size - sz, "(");
+
+      for (size_t i=0; i<node->children.size; i++)
+        {
+          if (i > 0)
+            {
+              sz += snprintf(buffer +sz, size - sz, ",");
+            }
+
+          sz += node_str((node_t*) node->children.data[i], buffer + sz, size - sz);
+        }
+
+      sz += snprintf(buffer +sz, size - sz, ")");
+    }
+
+  return sz;
+}
diff --git a/lib/node.h b/lib/node.h
new file mode 100644
index 0000000..92e4787
--- /dev/null
+++ b/lib/node.h
@@ -0,0 +1,31 @@
+#ifndef RZ_NODE_H
+#define RZ_NODE_H
+
+#include "commons.h"
+
+#define NODE_TYPE(G)                            \
+  G(NODE_MOD),                                  \
+    G(NODE_NUM)
+
+RZ_ENUM_H(NodeType, NODE_TYPE);
+
+typedef struct {
+  NodeType type;
+  str_t value;
+  int line;
+
+  struct {
+    struct node_t** data;
+    size_t size;
+    size_t cap;
+  } children;
+} node_t;
+
+void node_init(node_t* node, NodeType type, char* value, int line);
+void node_free(node_t* node);
+
+void node_add_child(node_t* node, node_t* child);
+
+size_t node_str(node_t* node, char* buffer, size_t size);
+
+#endif
diff --git a/lib/opcodes.c b/lib/opcodes.c
new file mode 100644
index 0000000..77da13a
--- /dev/null
+++ b/lib/opcodes.c
@@ -0,0 +1,3 @@
+#include "opcodes.h"
+
+RZ_ENUM_C(Opcode, OPCODES);
diff --git a/lib/opcodes.h b/lib/opcodes.h
new file mode 100644
index 0000000..77c7040
--- /dev/null
+++ b/lib/opcodes.h
@@ -0,0 +1,12 @@
+#ifndef RZ_OPCODES_H
+#define RZ_OPCODES_H
+
+#include "commons.h"
+
+#define OPCODES(G)                              \
+  G(OP_HALT),                                   \
+    G(OP_PUSH), G(OP_POP)
+
+RZ_ENUM_H(Opcode, OPCODES);
+
+#endif
diff --git a/lib/parser.c b/lib/parser.c
new file mode 100644
index 0000000..6583eca
--- /dev/null
+++ b/lib/parser.c
@@ -0,0 +1,83 @@
+#include "parser.h"
+#include "lib/lexer.h"
+#include "lib/node.h"
+
+void parser_init(parser_t* parser, lexer_t* lexer, err_t* err)
+{
+  assert(parser);
+  parser->lexer = lexer;
+  parser->err = err;
+}
+
+void parser_free(parser_t* parser)
+{
+  assert(parser);
+}
+
+node_t* parser_try_new_tree(parser_t* parser)
+{
+  assert(parser);
+  return parser_try_new_mod(parser);
+}
+
+node_t* parser_try_new_mod(parser_t* parser)
+{
+  assert(parser);
+  node_t* mod = malloc(sizeof(node_t));
+  node_init(mod, NODE_MOD, "", parser->lexer->line);
+  size_t len = strlen(parser->lexer->source);
+
+  while (parser->lexer->cursor < len)
+    {
+      node_t* expr = parser_try_new_expr(parser);
+
+      if (expr)
+        {
+          node_add_child(mod, expr);
+        }
+      else
+        {
+          node_free(mod);
+          free(mod);
+          return NULL;
+        }
+    }
+
+  return mod;
+}
+
+node_t* parser_try_new_expr(parser_t* parser)
+{
+  assert(parser);
+  return parser_try_new_num(parser);
+}
+
+node_t* parser_try_new_num(parser_t* parser)
+{
+  assert(parser);
+  return parser_try_new_consume(parser, NODE_NUM);
+}
+
+node_t* parser_try_new_consume(parser_t* parser, NodeType type)
+{
+  assert(parser);
+  node_t* next = lexer_try_new_next(parser->lexer);
+
+  if (!next)
+    {
+      return NULL;
+    }
+
+  if (next->type != type)
+    {
+      size_t const SZ = RZ_STR_LIMIT;
+      char err_msg[SZ];
+      snprintf(err_msg, SZ, "unexpected node '%s'", NodeTypeStr[next->type]);
+      err_error(parser->err, err_msg, next->line);
+      node_free(next);
+      free(next);
+      return NULL;
+    }
+
+  return next;
+}
diff --git a/lib/parser.h b/lib/parser.h
new file mode 100644
index 0000000..d259c72
--- /dev/null
+++ b/lib/parser.h
@@ -0,0 +1,23 @@
+#ifndef RZ_PARSER_H
+#define RZ_PARSER_H
+
+#include "commons.h"
+#include "err.h"
+#include "lexer.h"
+
+typedef struct {
+  lexer_t* lexer;
+  err_t* err;
+} parser_t;
+
+void parser_init(parser_t* parser, lexer_t* lexer, err_t* err);
+void parser_free(parser_t* parser);
+
+node_t* parser_try_new_tree(parser_t* parser);
+node_t* parser_try_new_mod(parser_t* parser);
+node_t* parser_try_new_expr(parser_t* parser);
+node_t* parser_try_new_num(parser_t* parser);
+
+node_t* parser_try_new_consume(parser_t* parser, NodeType type);
+
+#endif
diff --git a/lib/str.c b/lib/str.c
new file mode 100644
index 0000000..17548f8
--- /dev/null
+++ b/lib/str.c
@@ -0,0 +1,67 @@
+#include "str.h"
+
+void str_init(str_t* str)
+{
+  assert(str);
+  str->data = NULL;
+  str->size = 0;
+  str->cap = 0;
+}
+
+void str_free(str_t* str)
+{
+  assert(str);
+
+  free(str->data);
+  str->data = NULL;
+  str->size = 0;
+  str->cap = 0;
+}
+
+void str_resize(str_t* str)
+{
+  assert(str);
+
+  if (str->data == NULL)
+    {
+      str->cap = 2;
+      str->data = calloc(str->cap + 1, sizeof(char));
+    }
+
+  if (str->size >= str->cap)
+    {
+      str->cap *= 2;
+      str->data = realloc(str->data, sizeof(char) * (str->cap + 1));
+    }
+}
+
+void str_push(str_t* str, char c)
+{
+  assert(str);
+
+  str_resize(str);
+  str->data[str->size] = c;
+
+  str_resize(str);
+  str->data[str->size + 1] = '\0';
+  str->size++;
+}
+
+void str_append(str_t* str, char const* src)
+{
+  assert(str);
+  assert(src);
+
+  size_t len = strlen(src);
+
+  for (size_t i=0; i<len; i++)
+    {
+      str_push(str, src[i]);
+    }
+}
+
+int str_empty(str_t* str)
+{
+  assert(str);
+  return str->size == 0;
+}
diff --git a/lib/str.h b/lib/str.h
new file mode 100644
index 0000000..6b70696
--- /dev/null
+++ b/lib/str.h
@@ -0,0 +1,22 @@
+#ifndef RZ_STR_H
+#define RZ_STR_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+typedef struct {
+  char* data;
+  size_t size;
+  size_t cap;
+} str_t;
+
+void str_init(str_t* str);
+void str_free(str_t* str);
+
+void str_resize(str_t* str);
+void str_push(str_t* str, char c);
+void str_append(str_t* str, char const* src);
+int str_empty(str_t* str);
+
+#endif
diff --git a/lib/type.c b/lib/type.c
new file mode 100644
index 0000000..bda4886
--- /dev/null
+++ b/lib/type.c
@@ -0,0 +1,22 @@
+#include "type.h"
+
+RZ_ENUM_C(TypeKind, TYPE_KIND);
+
+void type_init(type_t* type, TypeKind kind)
+{
+  assert(type);
+  type->kind = kind;
+}
+
+void type_free(type_t* type)
+{
+  assert(type);
+}
+
+int type_eq(type_t* type, type_t* rhs)
+{
+  assert(type);
+  assert(rhs);
+
+  return type->kind == rhs->kind;
+}
diff --git a/lib/type.h b/lib/type.h
new file mode 100644
index 0000000..f0e4331
--- /dev/null
+++ b/lib/type.h
@@ -0,0 +1,20 @@
+#ifndef RZ_TYPE_H
+#define RZ_TYPE_H
+
+#include "commons.h"
+
+#define TYPE_KIND(G)                            \
+  G(TYPE_NUM)
+
+RZ_ENUM_H(TypeKind, TYPE_KIND);
+
+typedef struct {
+  TypeKind kind;
+} type_t;
+
+void type_init(type_t* type, TypeKind kind);
+void type_free(type_t* type);
+
+int type_eq(type_t* type, type_t* rhs);
+
+#endif
diff --git a/lib/tysy.c b/lib/tysy.c
new file mode 100644
index 0000000..5984655
--- /dev/null
+++ b/lib/tysy.c
@@ -0,0 +1,67 @@
+#include "tysy.h"
+
+void tysy_init(tysy_t* tysy)
+{
+  assert(tysy);
+  tysy->size = 0;
+
+  // num
+  {
+    type_t* num = malloc(sizeof(type_t));
+    type_init(num, TYPE_NUM);
+    tysy_register_new_type(tysy, "num", num);
+  }
+}
+
+void tysy_free(tysy_t* tysy)
+{
+  assert(tysy);
+
+  for (size_t i=0; i<tysy->size; i++)
+    {
+      type_free(tysy->types[i]);
+      free(tysy->types[i]);
+      free(tysy->names[i]);
+    }
+
+  tysy->size = 0;
+}
+
+void tysy_register_new_type(tysy_t* tysy, char* name, type_t* type)
+{
+  assert(tysy);
+  assert(name);
+  assert(type);
+  assert(tysy->size + 1 < RZ_MAX_TYPES);
+
+  tysy->types[tysy->size] = type;
+  tysy->names[tysy->size] = strdup(name);
+  tysy->size++;
+}
+
+type_t* tysy_try_find_type(tysy_t* tysy, char* name)
+{
+  assert(tysy);
+  assert(name);
+
+  for (size_t i=0; i<tysy->size; i++)
+    {
+      if (strcmp(name, tysy->names[i]) == 0)
+        {
+          return tysy->types[i];
+        }
+    }
+
+  return NULL;
+}
+
+value_t* tysy_new_num(tysy_t* tysy, double value)
+{
+  assert(tysy);
+
+  value_t* val = malloc(sizeof(value_t));
+  value_init(val, tysy_try_find_type(tysy, "num"));
+  val->value.num = value;
+
+  return val;
+}
diff --git a/lib/tysy.h b/lib/tysy.h
new file mode 100644
index 0000000..1719120
--- /dev/null
+++ b/lib/tysy.h
@@ -0,0 +1,21 @@
+#ifndef RZ_TYSY_H
+#define RZ_TYSY_H
+
+#include "commons.h"
+#include "value.h"
+
+typedef struct {
+  type_t* types[RZ_MAX_TYPES];
+  char* names[RZ_MAX_TYPES];
+  size_t size;
+} tysy_t;
+
+void tysy_init(tysy_t* tysy);
+void tysy_free(tysy_t* tysy);
+
+void tysy_register_new_type(tysy_t* tysy, char* name, type_t* type);
+type_t* tysy_try_find_type(tysy_t* tysy, char* name);
+
+value_t* tysy_new_num(tysy_t* tysy, double value);
+
+#endif
diff --git a/lib/value.c b/lib/value.c
new file mode 100644
index 0000000..44bb89a
--- /dev/null
+++ b/lib/value.c
@@ -0,0 +1,52 @@
+#include "value.h"
+
+void value_init(value_t* value, type_t* type)
+{
+  assert(value);
+  assert(type);
+
+  value->type = type;
+}
+
+void value_free(value_t* value)
+{
+  assert(value);
+}
+
+int value_eq(value_t* value, value_t* rhs)
+{
+  if (!type_eq(value->type, rhs->type))
+    {
+      return 0;
+    }
+
+  switch (value->type->kind)
+    {
+    case TYPE_NUM: {
+      return value->value.num == rhs->value.num;
+    } break;
+
+    default: {
+      fprintf(stderr, "Cannot compare value of type '%s'.\n",
+              TypeKindStr[value->type->kind]);
+      abort();
+    };
+    }
+
+  return 0;
+}
+
+size_t value_str(value_t* value, char* buffer, size_t size)
+{
+  assert(value);
+  assert(buffer);
+
+  switch (value->type->kind)
+    {
+    case TYPE_NUM:
+      return snprintf(buffer, size, "%lf", value->value.num);
+      break;
+
+    default: return 0;
+    }
+}
diff --git a/lib/value.h b/lib/value.h
new file mode 100644
index 0000000..bc96092
--- /dev/null
+++ b/lib/value.h
@@ -0,0 +1,22 @@
+#ifndef RZ_VALUE_H
+#define RZ_VALUE_H
+
+#include "type.h"
+
+typedef struct {
+  type_t* type;
+
+  union {
+    double num;
+  } value;
+
+} value_t;
+
+void value_init(value_t* value, type_t* type);
+void value_free(value_t* value);
+
+int value_eq(value_t* value, value_t* rhs);
+
+size_t value_str(value_t* value, char* buffer, size_t size);
+
+#endif
diff --git a/lib/vm.c b/lib/vm.c
new file mode 100644
index 0000000..f977ca9
--- /dev/null
+++ b/lib/vm.c
@@ -0,0 +1,70 @@
+#include "vm.h"
+#include "lib/commons.h"
+
+void vm_init(vm_t* vm)
+{
+  assert(vm);
+
+  vm->pc = 0;
+  vm->bp = 0;
+  vm->sp = 0;
+}
+
+void vm_free(vm_t* vm)
+{
+  assert(vm);
+}
+
+size_t vm_stack_str(vm_t* vm, char* buffer, size_t size)
+{
+  assert(vm);
+  assert(buffer);
+
+  size_t sz = 0;
+
+  for (size_t i=0; i<vm->sp; i++)
+    {
+      sz += snprintf(buffer + sz, size - sz, "| %d |\n", vm->stack[vm->sp - 1 - i]);
+    }
+
+  return sz;
+}
+
+void vm_exec_mod(vm_t* vm, mod_t* mod)
+{
+  assert(vm);
+  vm->pc = 0;
+
+  while (vm->pc < mod->program.size)
+    {
+      vm_exec_instr(vm, mod->program.ops[vm->pc],
+                    mod->program.params[vm->pc]);
+    }
+}
+
+void vm_exec_instr(vm_t* vm, Opcode op, param_t param)
+{
+  assert(vm);
+
+  switch (op)
+    {
+
+    case OP_PUSH: {
+      if (vm->sp + 1 >= RZ_STACK_LIMIT)
+        {
+          fprintf(stderr, "Stack overflow\n");
+          abort();
+        }
+
+      vm->stack[vm->sp] = param;
+      vm->sp++;
+      vm->pc++;
+    } break;
+
+    default: {
+      fprintf(stderr, "Cannot execute unknown opcode '%s'.\n",
+              OpcodeStr[op]);
+      abort();
+    };
+    }
+}
diff --git a/lib/vm.h b/lib/vm.h
new file mode 100644
index 0000000..ace7d1a
--- /dev/null
+++ b/lib/vm.h
@@ -0,0 +1,23 @@
+#ifndef RZ_VM_H
+#define RZ_VM_H
+
+#include "commons.h"
+#include "opcodes.h"
+#include "mod.h"
+
+typedef struct {
+  param_t stack[RZ_STACK_LIMIT];
+  size_t pc;
+  size_t bp;
+  size_t sp;
+} vm_t;
+
+void vm_init(vm_t* vm);
+void vm_free(vm_t* vm);
+
+size_t vm_stack_str(vm_t* vm, char* buffer, size_t size);
+
+void vm_exec_mod(vm_t* vm, mod_t* mod);
+void vm_exec_instr(vm_t* vm, Opcode op, param_t param);
+
+#endif
diff --git a/meson.build b/meson.build
index 32e4d00..3f41da5 100644
--- a/meson.build
+++ b/meson.build
@@ -16,6 +16,28 @@ configure_file(
 roza_lib = static_library(
   'roza',
   sources: [
+    # utils
+    'lib/str.c',
+
+    # core
+    'lib/err.c',
+    'lib/loader.c',
+
+    # lang
+    'lib/node.c',
+    'lib/lexer.c',
+    'lib/parser.c',
+    'lib/type.c',
+    'lib/value.c',
+    'lib/tysy.c',
+
+    # comp
+    'lib/opcodes.c',
+    'lib/mod.c',
+    'lib/compiler.c',
+
+    # exec
+    'lib/vm.c',
   ]
 )
 
@@ -35,7 +57,8 @@ executable('roza',
 
 executable('roza-tests',
            sources: [
-             'tests/units/trivial.c'
+             'tests/units/lexer.c',
+             'tests/units/parser.c',
            ],
            dependencies: [
              roza_dep,
diff --git a/src/main.c b/src/main.c
index 4e40e7e..b2e9863 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,8 +1,64 @@
-#include <stdio.h>
-#include <conf.h>
+#include <getopt.h>
+#include <commons.h>
+#include <loader.h>
 
-int main()
+int main(int argc, char** argv)
 {
-  printf("Roza v%s\n", ROZA_VERSION);
+  int index = 0;
+  int debug = 0;
+
+  while (1)
+    {
+      static struct option opts[] = {
+        {"help", no_argument, 0, 'h'},
+        {"version", no_argument, 0, 'v'},
+        {"debug", no_argument, 0, 'd'},
+        {0, 0, 0, 0}
+      };
+
+      char c = getopt_long(argc, argv, "hvd", opts, &index);
+
+      if (c == -1) { break; }
+
+      switch (c)
+        {
+        case 'h': {
+          printf("Usage: roza [OPTIONS] [SOURCE]\n");
+          printf("OPTIONS:\n");
+          printf("\t-d, --debug\tshow roza debug messages\n");
+          printf("\t-h, --help\tshow this message\n");
+          printf("\t-v, --version\tshow roza version\n");
+          exit(0);
+        } break;
+
+        case 'v': {
+          printf("Roza v%s\n", ROZA_VERSION);
+          printf("License GPLv3+\n");
+          exit(0);
+        } break;
+
+        case 'd': {
+          printf("Roza v%s: Debug mode enabled\n", ROZA_VERSION);
+          debug = 1;
+        } break;
+
+        default:
+          break;
+        }
+    }
+
+  if (optind < argc)
+    {
+      loader_t loader;
+      loader_init(&loader);
+
+      while (optind < argc)
+        {
+          loader_ldfile(&loader, argv[optind++], debug);
+        }
+
+      loader_free(&loader);
+    }
+
   return 0;
 }
diff --git a/tests/units/lexer.c b/tests/units/lexer.c
new file mode 100644
index 0000000..458eab6
--- /dev/null
+++ b/tests/units/lexer.c
@@ -0,0 +1,83 @@
+#include <stdarg.h>
+#include <criterion/criterion.h>
+#include <lexer.h>
+
+static void test_lexer_ok(char const* oracle, char const* source)
+{
+  lexer_t lex;
+  lexer_init(&lex, source, NULL);
+
+  node_t* tok = lexer_try_new_next(&lex);
+  cr_assert(tok != NULL);
+
+  size_t const SZ = 512;
+  char str[SZ];
+  node_str(tok, str, SZ);
+
+  cr_assert_str_eq(str, oracle);
+
+  node_free(tok);
+  lexer_free(&lex);
+}
+
+static void test_lexer_ko(char const* source)
+{
+  lexer_t lex;
+  err_t err;
+  err_init(&err);
+
+  lexer_init(&lex, source, &err);
+
+  node_t* tok = lexer_try_new_next(&lex);
+
+  cr_assert(tok == NULL);
+  cr_assert(err.size > 0);
+
+  err_free(&err);
+  lexer_free(&lex);
+}
+
+static void test_lexer(char const* source, size_t n, ...)
+{
+  va_list lst;
+  va_start(lst, n);
+
+  lexer_t lexer;
+  lexer_init(&lexer, source, NULL);
+
+  for (size_t i=0; i<n; i++)
+    {
+      node_t* tok = lexer_try_new_next(&lexer);
+      cr_assert(NULL != tok);
+
+      size_t const SZ = 256;
+      char tok_str[SZ];
+      node_str(tok, tok_str, SZ);
+
+      char* oracle = va_arg(lst, char*);
+      cr_assert_str_eq(oracle, tok_str);
+
+      node_free(tok);
+    }
+
+  lexer_free(&lexer);
+  va_end(lst);
+}
+
+Test(lexer, num) {
+  test_lexer_ok("NUM[35]", " 35 ");
+  test_lexer_ok("NUM[-270]", " -270 ");
+  test_lexer_ok("NUM[0.7]", "0.7");
+  test_lexer_ok("NUM[3.]", "3.");
+  test_lexer_ok("NUM[.4]", ".4");
+  test_lexer_ok("NUM[-3.14]", "-3.14");
+
+  test_lexer("-2 4.1 6", 3,
+             "NUM[-2]",
+             "NUM[4.1]",
+             "NUM[6]");
+
+  test_lexer_ko("-3..14");
+  test_lexer_ko("..2");
+  test_lexer_ko("2..");
+}
diff --git a/tests/units/parser.c b/tests/units/parser.c
new file mode 100644
index 0000000..967f9c4
--- /dev/null
+++ b/tests/units/parser.c
@@ -0,0 +1,60 @@
+#include <criterion/criterion.h>
+#include <lexer.h>
+#include <parser.h>
+
+static void test_parser_ok(char const* oracle, char const* source)
+{
+  err_t err;
+  err_init(&err);
+
+  lexer_t lex;
+  lexer_init(&lex, source, &err);
+
+  parser_t parser;
+  parser_init(&parser, &lex, &err);
+
+  node_t* node = parser_try_new_tree(&parser);
+
+  cr_assert(NULL != node);
+
+  size_t const SZ = 256;
+  char msg[SZ];
+  node_str(node, msg, SZ);
+
+  cr_assert_str_eq(msg, oracle);
+
+  node_free(node);
+  free(node);
+
+  parser_free(&parser);
+  lexer_free(&lex);
+  err_free(&err);
+}
+
+static void test_parser_ko(char const* source)
+{
+  err_t err;
+  err_init(&err);
+
+  lexer_t lex;
+  lexer_init(&lex, source, &err);
+
+  parser_t parser;
+  parser_init(&parser, &lex, &err);
+
+  node_t* node = parser_try_new_tree(&parser);
+
+  cr_assert(NULL == node);
+  cr_assert_gt(err.size, 0);
+
+  parser_free(&parser);
+  lexer_free(&lex);
+  err_free(&err);
+}
+
+Test(parser, num) {
+  test_parser_ok("MOD", "");
+  test_parser_ok("MOD(NUM[37],NUM[29])", "37 29");
+
+  test_parser_ko(" § ");
+}
diff --git a/tests/units/trivial.c b/tests/units/trivial.c
deleted file mode 100644
index a89a2e0..0000000
--- a/tests/units/trivial.c
+++ /dev/null
@@ -1,5 +0,0 @@
-#include <criterion/criterion.h>
-
-Test(trivial, trivial) {
-  cr_assert(1 + 1 == 2);
-}