diff --git a/code/compiler/03/ast.cpp b/code/compiler/03/ast.cpp
new file mode 100644
index 0000000..734a54a
--- /dev/null
+++ b/code/compiler/03/ast.cpp
@@ -0,0 +1 @@
+#include "ast.hpp"
diff --git a/code/compiler/03/ast.hpp b/code/compiler/03/ast.hpp
index 70c2af9..e1629cd 100644
--- a/code/compiler/03/ast.hpp
+++ b/code/compiler/03/ast.hpp
@@ -1,6 +1,7 @@
 #pragma once
 #include <memory>
 #include <vector>
+#include "type.hpp"
 
 struct ast {
     virtual ~ast() = default;
diff --git a/code/compiler/03/type.cpp b/code/compiler/03/type.cpp
new file mode 100644
index 0000000..206a9aa
--- /dev/null
+++ b/code/compiler/03/type.cpp
@@ -0,0 +1,25 @@
+#include "type.hpp"
+#include <sstream>
+#include <algorithm>
+
+std::string type_mgr::new_type_name() {
+    std::ostringstream oss;
+    int temp = last_id++;
+
+    do {
+        oss << (char) ('a' + (temp % 26));
+        temp /= 26;
+    } while(temp);
+    std::string str = oss.str();
+
+    std::reverse(str.begin(), str.end());
+    return str;
+};
+
+type_ptr type_mgr::new_type() {
+    return type_ptr(new type_var(new_type_name()));
+}
+
+type_ptr type_mgr::new_arrow_type() {
+    return type_ptr(new type_arr(new_type(), new_type()));
+}
diff --git a/code/compiler/03/type.hpp b/code/compiler/03/type.hpp
new file mode 100644
index 0000000..752d778
--- /dev/null
+++ b/code/compiler/03/type.hpp
@@ -0,0 +1,39 @@
+#pragma once
+#include <memory>
+#include <map>
+
+struct type {
+    virtual ~type() = default;
+};
+
+using type_ptr = std::shared_ptr<type>;
+
+struct type_var : public type {
+    std::string name;
+
+    type_var(std::string n)
+        : name(std::move(n)) {}
+};
+
+struct type_id : public type {
+    int id;
+
+    type_id(int i) 
+        : id(i) {}
+};
+
+struct type_arr : public type {
+    type_ptr left;
+    type_ptr right;
+
+    type_arr(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+};
+
+struct type_mgr {
+    int last_id = 0;
+
+    std::string new_type_name();
+    type_ptr new_type();
+    type_ptr new_arrow_type();
+};