diff --git a/include/definitions.hpp b/include/definitions.hpp
index 8b2fb76..bdf1b3b 100644
--- a/include/definitions.hpp
+++ b/include/definitions.hpp
@@ -45,7 +45,7 @@ struct AnyType {
 };
 
 struct Type {
-  std::variant<AbstractType, AliasType, AnyType> type;
+  std::variant<AliasType, AnyType> type;
 };
 
 struct Constructor {
@@ -85,7 +85,6 @@ struct Namespace {
   enum Modifier { Const, Var };
 
   std::unordered_map<std::string, utils::IdType> types;
-  std::unordered_map<std::string, utils::IdType> typeclasses;
   std::unordered_map<std::string, utils::IdType> functions;
   std::unordered_map<std::string, utils::IdType> constructors;
   std::unordered_map<std::string, Namespace> namespaces;
diff --git a/include/global_info.hpp b/include/global_info.hpp
index f672a4e..b33dc79 100644
--- a/include/global_info.hpp
+++ b/include/global_info.hpp
@@ -6,7 +6,6 @@
 
 // for clangd
 #include "definitions.hpp"
-#include "type_manager.hpp"
 #include "utils.hpp"
 
 namespace info {
@@ -38,6 +37,9 @@ public:
 
     utils::IdType AddType(const std::string& type, definition::Type&& type_info);
 
+    utils::IdType AddAbstractType(const std::string& abstract_type,
+                                  definition::AbstractType&& abstract_type_info);
+
     utils::IdType AddTypeclass(const std::string& typeclass, definition::Typeclass&& typeclass_info);
 
     utils::IdType AddConstructor(const std::string& constructor,
@@ -55,20 +57,17 @@ public:
     std::optional<utils::IdType> FindType(const std::optional<std::vector<std::string>>& path,
                                           const std::string& type);
 
-    std::optional<utils::IdType> FindTypeclass(const std::optional<std::vector<std::string>>& path,
-                                               const std::string& typeclass);
+    std::optional<utils::IdType> FindAbstractType(const std::string& abstract_type);
+
+    std::optional<utils::IdType> FindTypeclass(const std::string& typeclass);
 
     std::optional<utils::IdType> FindConstructor(const std::optional<std::vector<std::string>>& path,
-                                                 const std::string& typeclass);
+                                                 const std::string& constructor);
 
     NamespaceVisitor CreateVisitor() {
       return global_info_.CreateVisitor();
     }
 
-    type::TypeManager* GetTypeManager() {
-      return global_info_.GetTypeManager();
-    }
-
     GlobalInfo* GetGlobalInfo() {
       return &global_info_;
     }
@@ -97,10 +96,6 @@ public:
     return NamespaceVisitor(*this);
   }
 
-  type::TypeManager* GetTypeManager() {
-    return &type_manager_;
-  }
-
   // TODO: remember about vector realloc
   definition::Function* GetFunctionInfo(utils::IdType id) {
     return &functions_[id];
@@ -124,10 +119,12 @@ public:
 private:
   std::vector<definition::Function> functions_;
   std::vector<definition::Type> types_;
+  std::vector<definition::AbstractType> abstract_types_;
   std::vector<definition::Typeclass> typeclasses_;
   std::vector<definition::Constructor> constructors_;
 
-  type::TypeManager type_manager_;
+  std::unordered_map<std::string, utils::IdType> name_to_typeclass_;
+  std::unordered_map<std::string, utils::IdType> name_to_abstract_type_;
 
   definition::Namespace global_namespace_;
   std::vector<definition::Import> imports_;
diff --git a/include/interpreter_tree.hpp b/include/interpreter_tree.hpp
index 48b16b7..50770d5 100644
--- a/include/interpreter_tree.hpp
+++ b/include/interpreter_tree.hpp
@@ -297,7 +297,8 @@ struct Namespace {
   TypeIdentifier type;
   NamespaceSources scope;
 
-  std::optional<utils::IdType> type_id_;
+  std::optional<utils::IdType> link_type_id_;
+  std::optional<utils::IdType> link_typeclass_id_;
 };
 
 // ----------------- Definitions -----------------
@@ -570,7 +571,7 @@ struct ExtendedScopedAnyType {
 struct TypeclassExpression {
     TypeclassSubExpression typeclass;
 
-    utils::IdType type_id_;
+    utils::IdType typeclass_id_;
 };
 
 struct ParametrizedTypeclass {
diff --git a/include/link_symbols_visitor.hpp b/include/link_symbols_visitor.hpp
index beb43c9..30c1a25 100644
--- a/include/link_symbols_visitor.hpp
+++ b/include/link_symbols_visitor.hpp
@@ -17,30 +17,30 @@ public:
 private:
   // Sources -----------------
 
-  void Visit(SourceFile* node) override;
+  // // void Visit(SourceFile* node) override;
 
   // Namespaces, partitions -----------------
 
-  void Visit(PartitionSources* node) override;
-  void Visit(Partition* node) override;
-  void Visit(NamespaceSources* node) override;
+  // // void Visit(PartitionSources* node) override;
+  // // void Visit(Partition* node) override;
+  // // void Visit(NamespaceSources* node) override;
   void Visit(Namespace* node) override;
 
   // Definitions -----------------
 
-  void Visit(ImportStatement* node) override;
-  void Visit(AliasDefinitionStatement* node) override;
-  void Visit(VariableDefinitionStatement* node) override;
-  void Visit(FunctionDeclaration* node) override;
-  void Visit(FunctionDefinitionStatement* node) override;
-  void Visit(TypeDefinitionStatement* node) override;
-  void Visit(AbstractTypeDefinitionStatement* node) override;
-  void Visit(TypeclassDefinitionStatement* node) override;
+  // // void Visit(ImportStatement* node) override;
+  // // void Visit(AliasDefinitionStatement* node) override;
+  // // void Visit(VariableDefinitionStatement* node) override;
+  // // void Visit(FunctionDeclaration* node) override;
+  // // void Visit(FunctionDefinitionStatement* node) override;
+  // // void Visit(TypeDefinitionStatement* node) override;
+  // // void Visit(AbstractTypeDefinitionStatement* node) override;
+  // // void Visit(TypeclassDefinitionStatement* node) override;
 
   // Definition parts
 
-  void Visit(FunctionDefinition* node) override;
-  void Visit(TypeDefinition* node) override;
+  // // void Visit(FunctionDefinition* node) override;
+  // // void Visit(TypeDefinition* node) override;
   // // void Visit(AnyAnnotatedType* node) override;
 
   // Flow control -----------------
@@ -76,7 +76,7 @@ private:
   // // void Visit(ReturnExpression* node) override;
   // // void Visit(TypeConstructorParameter* node) override;
   // // void Visit(TypeConstructor* node) override;
-  void Visit(LambdaFunction* node) override;
+  // // void Visit(LambdaFunction* node) override;
   // // void Visit(ArrayExpression* node) override;
 
   // // void Visit(LoopControlExpression& node) override; // enum
@@ -95,13 +95,13 @@ private:
   // // void Visit(FunctionType* node) override;
   // // void Visit(TupleType* node) override;
   // // void Visit(VariantType* node) override;
-  void Visit(TypeExpression* node) override; // TODO
+  void Visit(TypeExpression* node) override;
 
   // // void Visit(ExtendedScopedAnyType* node) override;
 
   // Typeclass
 
-  void Visit(TypeclassExpression* node) override; // TODO
+  void Visit(TypeclassExpression* node) override;
   // // void Visit(ParametrizedTypeclass* node) override;
 
   // Typeclass & Type
diff --git a/include/type_check_visitor.hpp b/include/type_check_visitor.hpp
index 299e247..4751152 100644
--- a/include/type_check_visitor.hpp
+++ b/include/type_check_visitor.hpp
@@ -10,8 +10,8 @@ namespace interpreter {
 
 class TypeCheckVisitor : public Visitor {
 public:
-  explicit TypeCheckVisitor(info::GlobalInfo& global_info)
-    : namespace_visitor_(global_info.CreateVisitor()) {}
+  explicit TypeCheckVisitor(info::GlobalInfo& global_info, info::TypeInfoContextManager& context_manager)
+    : namespace_visitor_(global_info.CreateVisitor()), context_manager_(context_manager) {}
 
 private:
   // Sources -----------------
@@ -122,7 +122,7 @@ private:
 
 private:
   info::GlobalInfo::NamespaceVisitor namespace_visitor_;
-  info::TypeInfoContextManager context_manager_;
+  info::TypeInfoContextManager& context_manager_;
 
   utils::IdType current_type_;
   std::optional<utils::IdType> returned_type_;
diff --git a/include/type_info_contexts.hpp b/include/type_info_contexts.hpp
index 337e0bb..24be4ad 100644
--- a/include/type_info_contexts.hpp
+++ b/include/type_info_contexts.hpp
@@ -1,11 +1,13 @@
 #pragma once
 
+#include <cstddef>
 #include <string>
 #include <vector>
 #include <unordered_map>
 
 // for clangd
-#include "types_info.hpp"
+#include "error_handling.hpp"
+#include "types.hpp"
 #include "utils.hpp"
 
 namespace info {
@@ -13,32 +15,10 @@ namespace info {
 // TODO: remember about typespointers
 class TypeInfoContextManager {
 public:
-  template<typename T>
-  utils::IdType AddType(T&& type) {
-    types_.push_back(std::forward(type));
-    return types_.size() - 1;
+  type::TypeManager* GetTypeManager() {
+    return &type_manager_;
   }
 
-  const info::type::Type& GetType(utils::IdType type_id) {
-    return types_[type_id];
-  }
-
-  void AddTypeRequirement(utils::IdType type, utils::IdType requrement) {} // TODO
-  void EqualTypes(utils::IdType first_type, utils::IdType second_type) {} // TODO
-
-  // void CallFunction(const std::vector<std::string>& names,
-  //                   const std::vector<utils::IdType>& argument_types) {
-  //   if (names.size() != argument_types.size()) {
-  //     // error
-  //   }
-  //
-  //   contexts_.emplace_back(true);
-  //
-  //   for (size_t i = 0; i < names.size(); ++i) {
-  //     DefineVariable(names[i], argument_types[i]);
-  //   }
-  // }
-
   void EnterContext() {
     contexts_.emplace_back(false);
   }
@@ -60,6 +40,10 @@ public:
     return contexts_.back().DefineVariable(name, type_id);
   }
 
+  bool DefineLocalAbstractType() {
+    // TODO
+  }
+
   bool RemoveVariable(const std::string& name) {
     for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
       if (contexts_[i].RemoveVariable(name)) {
@@ -120,7 +104,7 @@ private:
   };
 
   std::vector<Context> contexts_;
-  std::vector<info::type::Type> types_;
+  type::TypeManager type_manager_;
 };
 
 } // namespace info
diff --git a/include/type_manager.hpp b/include/type_manager.hpp
deleted file mode 100644
index 4d33d4d..0000000
--- a/include/type_manager.hpp
+++ /dev/null
@@ -1,26 +0,0 @@
-#pragma once
-
-#include <vector>
-
-// for clangd
-#include "types.hpp"
-#include "utils.hpp"
-
-namespace info::type {
-
-class TypeManager {
-public:
-  template<typename T>
-  void AddType(const T& type) {
-    types_.emplace(type);
-  }
-
-  template<typename T>
-  T GetType(utils::IdType type_id) {
-    return std::get<T>(types_.at(type_id));
-  }
-private:
-  std::vector<Type> types_;
-};
-
-} // namespace info::type
diff --git a/include/types.hpp b/include/types.hpp
index 72d546f..0c0a358 100644
--- a/include/types.hpp
+++ b/include/types.hpp
@@ -4,68 +4,195 @@
 #include <string>
 #include <variant>
 #include <memory>
+#include <unordered_set>
 
 // for clangd
 #include "utils.hpp"
 
 namespace info::type {
 
-// // Temporary frozen, TODO
-// struct AbstractType {
-//   utils::IdType graph_id;
-//   std::vector<utils::IdType> paramaters;
-// };
+// TODO: move in constructors
 
-// TODO: check, if defined type is variant, etc.
-struct DefinedType {
-  utils::IdType type_id; // in defined types
-  utils::IdType type; // in types manager, created using context types
+class TypeManager;
+
+class AbstractType { // later will be found in context
+public:
+  AbstractType() = default;
+  AbstractType(const std::string& name,
+               const std::vector<utils::IdType>& requirements) : name_(name) {
+    for (auto& typeclass : requirements) {
+      requirements_.insert(typeclass);
+    }
+  }
+
+  bool Same(const AbstractType& type) const;
+  bool operator<(const AbstractType& type) const;
+  bool operator>(const AbstractType& type) const;
+private:
+  std::string name_;
+  std::unordered_set<utils::IdType> requirements_; // TODO: all typeclasses from tree
+};
+
+class DefinedType {
+public:
+  DefinedType() = default;
+  DefinedType(utils::IdType type_id,
+              utils::IdType type,
+              TypeManager* type_manager)
+    : type_id_(type_id), type_(type), type_manager_(type_manager) {}
+
+  bool Same(const DefinedType& type) const;
+  bool operator<(const DefinedType& type) const;
+  bool operator>(const DefinedType& type) const;
+private:
+  utils::IdType type_id_; // in defined types
+  utils::IdType type_; // in types manager, created using context types (if specific type)
+  TypeManager* type_manager_ = nullptr;
 };
 
 enum class InternalType {
-  Float,
-  Int,
-  String,
-  Char,
-  Bool,
-  Unit,
+  Float = 0,
+  Int = 1,
+  String = 2,
+  Char = 3,
+  Bool = 4,
+  Unit = 5,
 };
 
-struct TupleType {
-  std::optional<std::string> type;
-  std::vector<std::pair<std::optional<std::string>, utils::IdType>> fields;
+class TupleType {
+public:
+  TupleType() = default;
+  TupleType(const std::optional<std::string>& name,
+            const std::vector<std::pair<std::optional<std::string>, utils::IdType>>& fields,
+            TypeManager* type_manager)
+    : name_(name), fields_(fields), type_manager_(type_manager) {}
+
+  bool Same(const TupleType& type) const;
+  bool operator<(const TupleType& type) const;
+  bool operator>(const TupleType& type) const;
+private:
+  std::optional<std::string> name_;
+  std::vector<std::pair<std::optional<std::string>, utils::IdType>> fields_;
+  TypeManager* type_manager_ = nullptr;
 };
 
-struct VariantType {
-  std::optional<std::string> type;
-  std::vector<TupleType> constructors;
+class VariantType {
+public:
+  VariantType() = default;
+  VariantType(const std::optional<std::string>& name,
+              const std::vector<TupleType>& constructors)
+    : name_(name), constructors_(constructors){}
+
+  bool Same(const VariantType& type) const;
+  bool operator<(const VariantType& type) const;
+  bool operator>(const VariantType& type) const;
+private:
+  std::optional<std::string> name_;
+  std::vector<TupleType> constructors_;
 };
 
-struct OptionalType {
-  std::optional<utils::IdType> type; // Can be empty (Some or None)
+class OptionalType {
+public:
+  OptionalType() = default;
+  OptionalType(utils::IdType type,
+               TypeManager* type_manager)
+    : type_(type), type_manager_(type_manager) {}
+
+  bool Same(const OptionalType& type) const;
+  bool operator<(const OptionalType& type) const;
+  bool operator>(const OptionalType& type) const;
+private:
+  utils::IdType type_;
+  TypeManager* type_manager_ = nullptr;
 };
 
-struct ReferenceToType {
-  std::vector<utils::ReferenceType> references;
-  utils::IdType type;
+class ReferenceToType {
+public:
+  ReferenceToType() = default;
+  ReferenceToType(const std::vector<utils::ReferenceType>& references,
+                  utils::IdType type,
+                  TypeManager* type_manager)
+    : references_(references), type_(type), type_manager_(type_manager) {}
+
+  bool Same(const ReferenceToType& type) const;
+  bool operator<(const ReferenceToType& type) const;
+  bool operator>(const ReferenceToType& type) const;
+private:
+  std::vector<utils::ReferenceType> references_;
+  utils::IdType type_;
+  TypeManager* type_manager_ = nullptr;
 };
 
-struct FunctionType {
-  std::vector<utils::IdType> argument_types;
-  utils::IdType return_type;
+/////////////////////////////
+
+class FunctionType {
+public:
+  FunctionType() = default;
+  FunctionType(const std::vector<utils::IdType>& argument_types,
+               utils::IdType return_type,
+               TypeManager* type_manager)
+    : argument_types_(argument_types), return_type_(return_type), type_manager_(type_manager) {}
+
+  bool Same(const FunctionType& type) const;
+  bool operator<(const FunctionType& type) const;
+  bool operator>(const FunctionType& type) const;
+private:
+  std::vector<utils::IdType> argument_types_;
+  utils::IdType return_type_;
+  TypeManager* type_manager_ = nullptr;
 };
 
-struct ArrayType {
-  size_t size; // ?? = 0 for dynamic ??
-  std::optional<utils::IdType> elements_type;
+class ArrayType {
+public:
+  ArrayType() = default;
+  ArrayType(size_t size,
+            utils::IdType  elements_type,
+            TypeManager* type_manager)
+    : size_(size), elements_type_(elements_type), type_manager_(type_manager) {}
+
+  bool Same(const ArrayType& type) const;
+  bool operator<(const ArrayType& type) const;
+  bool operator>(const ArrayType& type) const;
+private:
+  size_t size_; // = 0 for dynamic
+  utils::IdType elements_type_;
+  TypeManager* type_manager_ = nullptr;
 };
 
-using Type = std::variant<DefinedType,
-                          InternalType,
-                          TupleType,
-                          VariantType,
-                          ReferenceToType,
-                          FunctionType,
-                          ArrayType>;
+class Type {
+public:
+  template<typename T>
+  explicit Type(T&& type) : type_(std::forward(type)) {}
+
+  bool Same(const Type& type) const; // some rule exceptions ??
+  bool operator<(const Type& type) const; // TODO: some rule exceptions ??
+  bool operator>(const Type& type) const;
+private:
+  std::variant<AbstractType,
+               DefinedType,
+               InternalType,
+               TupleType,
+               VariantType,
+               ReferenceToType,
+               FunctionType,
+               ArrayType> type_;
+};
+
+class TypeManager {
+public:
+  template<typename T>
+  utils::IdType AddType(const T&& type);
+
+  template<typename T>
+  std::optional<T*> GetType(utils::IdType type_id);
+
+  std::optional<Type*> GetAnyType(utils::IdType type_id);
+
+  void AddTypeRequirement(utils::IdType type, utils::IdType requrement); // TODO
+  void EqualTypes(utils::IdType first_type, utils::IdType second_type); // TODO
+private:
+  std::vector<info::type::Type> types_;
+};
 
 } // namespace info::type
+
diff --git a/include/utils.hpp b/include/utils.hpp
index cf13b62..de02aed 100644
--- a/include/utils.hpp
+++ b/include/utils.hpp
@@ -9,7 +9,7 @@ using std::size_t;
 
 using IdType = size_t;
 
-enum class ReferenceType { Reference, UniqueReference };
+enum class ReferenceType { Reference = 0, UniqueReference = 1 };
 
 template<typename T>
 class Storage {
diff --git a/src/find_symbols_visitor.cpp b/src/find_symbols_visitor.cpp
index b7b2802..4a91bf2 100644
--- a/src/find_symbols_visitor.cpp
+++ b/src/find_symbols_visitor.cpp
@@ -159,28 +159,24 @@ void FindSymbolsVisitor::Visit(TypeDefinitionStatement* node) {
 void FindSymbolsVisitor::Visit(AbstractTypeDefinitionStatement* node) {
   is_in_statement = true;
 
-  info::definition::Type info;
-
-  info::definition::AbstractType abstract_type_info;
+  info::definition::AbstractType info;
 
   Visit(node->type.get());
-  abstract_type_info.type = std::move(std::any_cast<info::definition::Parameter>(current_info_));
+  info.type = std::move(std::any_cast<info::definition::Parameter>(current_info_));
   current_info_.reset();
 
   switch (node->modifier) {
     case interpreter::AbstractTypeDefinitionStatement::Basic:
-      abstract_type_info.modifier = info::definition::AbstractType::Basic;
+      info.modifier = info::definition::AbstractType::Basic;
       break;
     case interpreter::AbstractTypeDefinitionStatement::Abstract:
-      abstract_type_info.modifier = info::definition::AbstractType::Abstract;
+      info.modifier = info::definition::AbstractType::Abstract;
       break;
   }
 
-  std::string type = abstract_type_info.type.type;
+  std::string type = info.type.type;
 
-  info.type = std::move(abstract_type_info);
-
-  node->type_id_ = namespace_visitor_.AddType(type, std::move(info));
+  node->type_id_ = namespace_visitor_.AddAbstractType(type, std::move(info));
 
   is_in_statement = false;
 }
diff --git a/src/global_info.cpp b/src/global_info.cpp
index bcf19a8..864d181 100644
--- a/src/global_info.cpp
+++ b/src/global_info.cpp
@@ -31,9 +31,17 @@ void GlobalInfo::NamespaceVisitor::AddEnterNamespace(const std::string& name,
   current_path_.push_back(name);
 }
 
-void GlobalInfo::NamespaceVisitor::EnterNamespace(const std::string& name) { // TODO: enter sibling namespace, etc.
-  namespace_stack_.push_back(&namespace_stack_.back()->namespaces[name]);
-  current_path_.push_back(name);
+void GlobalInfo::NamespaceVisitor::EnterNamespace(const std::string& name) {
+  for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
+    auto namespace_iter = namespace_stack_[i]->namespaces.find(name);
+    if (namespace_iter != namespace_stack_[i]->namespaces.end()) {
+      namespace_stack_.push_back(&namespace_iter->second);
+      current_path_.push_back(name);
+      return;
+    }
+  }
+
+  error_handling::HandleInternalError("Can't find namespace", "GlobalInfo.NamespaceVisitor.EnterNamespace");
 }
 
 void GlobalInfo::NamespaceVisitor::ExitNamespace() {
@@ -100,7 +108,7 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddFunctionDefinition(const std::str
 }
 
 // TODO: internal types, etc.
-// TODO: extended constructor names
+// TODO: extended constructor names (point separated names)
 utils::IdType GlobalInfo::NamespaceVisitor::AddType(const std::string& type,
                                                     definition::Type&& type_info) {
   size_t id = 0;
@@ -153,38 +161,44 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddType(const std::string& type,
   return id;
 }
 
-utils::IdType GlobalInfo::NamespaceVisitor::AddTypeclass(const std::string& typeclass,
-                                                         definition::Typeclass&& typeclass_info) {
-  size_t id = 0;
-
-  auto typeclass_id_iter = namespace_stack_.back()->typeclasses.find(typeclass);
-
-  if (typeclass_id_iter == namespace_stack_.back()->typeclasses.end()) {
-    id = global_info_.typeclasses_.size();
-    namespace_stack_.back()->typeclasses[typeclass] = id;
-    global_info_.typeclasses_.push_back(std::move(typeclass_info));
-  } else {
-    error_handling::HandleTypecheckError("More then one typeclass with the same name in namespace");
+// TODO: link abstract type with let definitions
+utils::IdType GlobalInfo::NamespaceVisitor::AddAbstractType(const std::string& abstract_type,
+                                                            definition::AbstractType&& abstract_type_info) {
+  if (!FindAbstractType(abstract_type).has_value()) {
+    size_t id = global_info_.abstract_types_.size();
+    global_info_.name_to_abstract_type_[abstract_type] = id;
+    global_info_.abstract_types_.push_b(ack(std::move(abstract_type_info));
   }
 
-  return id;
+  error_handling::HandleTypecheckError("More then one abstract type with the same name in namespace");
+  return 0;
+}
+
+utils::IdType GlobalInfo::NamespaceVisitor::AddTypeclass(const std::string& typeclass,
+                                                         definition::Typeclass&& typeclass_info) {
+  if (!FindTypeclass(typeclass).has_value()) {
+    size_t id = global_info_.typeclasses_.size();
+    global_info_.name_to_typeclass_[typeclass] = id;
+    global_info_.typeclasses_.push_back(std::move(typeclass_info));
+  }
+
+
+  error_handling::HandleTypecheckError("More then one typeclass with the same name in namespace");
+  return 0;
 }
 
 utils::IdType GlobalInfo::NamespaceVisitor::AddConstructor(const std::string& constructor,
                                                            definition::Constructor&& constructor_info) {
-  size_t id = 0;
-
   auto constructor_id_iter = namespace_stack_.back()->constructors.find(constructor);
 
   if (constructor_id_iter == namespace_stack_.back()->constructors.end()) {
-    id = global_info_.constructors_.size();
+    size_t id = global_info_.constructors_.size();
     namespace_stack_.back()->constructors[constructor] = id;
     global_info_.constructors_.push_back(std::move(constructor_info));
-  } else {
-    error_handling::HandleTypecheckError("More then one constructor with the same name in namespace");
   }
 
-  return id;
+  error_handling::HandleTypecheckError("More then one constructor with the same name in namespace");
+  return 0;
 }
 
 std::optional<definition::Namespace*> GlobalInfo::NamespaceVisitor::FindNamespace(const std::optional<std::vector<std::string>>& path) {
@@ -247,19 +261,24 @@ std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindType(
   });
 }
 
-std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindTypeclass(
-    const std::optional<std::vector<std::string>>& path,
-    const std::string& typeclass) {
-  return FindSomething<utils::IdType>(path,
-      [typeclass] (definition::Namespace* current_namespace) -> std::optional<utils::IdType> {
+std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindAbstractType(const std::string& abstract_type) {
+  auto abstract_type_id_iter = global_info_.name_to_abstract_type_.find(abstract_type);
 
-    auto typeclass_info_iter = current_namespace->typeclasses.find(typeclass);
-    if (typeclass_info_iter == current_namespace->typeclasses.end()) {
-      return std::nullopt;
-    }
+  if (abstract_type_id_iter != global_info_.name_to_abstract_type_.end()) {
+    return abstract_type_id_iter->second;
+  }
 
-    return typeclass_info_iter->second;
-  });
+  return std::nullopt;
+}
+
+std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindTypeclass(const std::string& typeclass) {
+  auto typeclass_id_iter = global_info_.name_to_typeclass_.find(typeclass);
+
+  if (typeclass_id_iter != global_info_.name_to_typeclass_.end()) {
+    return typeclass_id_iter->second;
+  }
+
+  return std::nullopt;
 }
 
 std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindConstructor(
diff --git a/src/link_symbols_visitor.cpp b/src/link_symbols_visitor.cpp
index 26de5f3..48356a1 100644
--- a/src/link_symbols_visitor.cpp
+++ b/src/link_symbols_visitor.cpp
@@ -4,187 +4,57 @@
 
 namespace interpreter {
 
-// Sources -----------------
-
-void LinkSymbolsVisitor::Visit(SourceFile* node) {
-  for (auto& statement : node->statements) {
-    if (std::holds_alternative<Partition>(statement)) {
-      Visit(&std::get<Partition>(statement));
-    } else if (std::holds_alternative<SourceStatement>(statement)) {
-      Visitor::Visit(std::get<SourceStatement>(statement));
-    } else {
-      // error
-    }
+const std::string& NameFromTypeSubExpression(const TypeSubExpression& type) {
+  if (std::holds_alternative<std::unique_ptr<std::string>>(type)) {
+    return *std::get<std::unique_ptr<std::string>>(type);
+  } else if (std::holds_alternative<std::unique_ptr<ParametrizedType>>(type)) {
+    return std::get<std::unique_ptr<ParametrizedType>>(type)->type;
   }
-}
 
-void LinkSymbolsVisitor::Visit(Sources* node) {
-  abstract_types_.EnterContext();
-  for (auto& statement : node->statements) {
-    Visitor::Visit(statement);
-  }
-  abstract_types_.ExitContext();
+  error_handling::HandleInternalError("Empty variant", "NameFromTypeSubExpression");
+  exit(1); // TODO: better decision ??
 }
 
 // Namespaces, partitions -----------------
 
-void LinkSymbolsVisitor::Visit(Partition* node) {
-  // TODO
-  Visit(node->scope.get());
-}
-
 void LinkSymbolsVisitor::Visit(Namespace* node) {
-  node->type_id_ = namespace_visitor_.FindType({}, node->type);
+  // Visitor::Visit(&node->type); // not needed
 
-  if (node->name.has_value() && !node->type_id_.has_value()) {
-    error_handling::HandleTypecheckError("Variable namespace type not found");
+  auto maybe_type = namespace_visitor_.FindType(std::nullopt, node->type); // TODO: find only in local namespace
+  auto maybe_typeclass = namespace_visitor_.FindType(std::nullopt, node->type); // TODO: find only if in global namespace
+  if (maybe_type.has_value() && maybe_typeclass.has_value()) {
+    error_handling::HandleTypecheckError("Ambigious namespace name (typeclass or type)");
+  }
+  if (maybe_type.has_value()) {
+    node->link_type_id_ = maybe_type.value();
+  }
+  if (maybe_typeclass.has_value()) {
+    node->link_typeclass_id_ = maybe_typeclass.value();
   }
 
   namespace_visitor_.EnterNamespace(node->type);
-  Visit(node->scope.get());
+
+  Visitor::Visit(&node->scope);
+
   namespace_visitor_.ExitNamespace();
 }
 
-// Definitions -----------------
-
-void LinkSymbolsVisitor::Visit(ImportStatement* node) {}
-
-void LinkSymbolsVisitor::Visit(AliasDefinitionStatement* node) {
-  abstract_types_.EnterContext();
-  for (size_t i = 0; i <node->parameters.size(); ++i) {
-    abstract_types_.DefineType(node->parameters[i], node->parameter_graph_ids_[i]);
-  }
-  Visitor::Visit(node->value.get());
-  abstract_types_.ExitContext();
-}
-
-void LinkSymbolsVisitor::Visit(VariableDefinitionStatement* node) {
-  abstract_types_.EnterContext();
-  Visitor::Visit(node->name);
-  Visitor::Visit(node->value);
-  abstract_types_.ExitContext();
-}
-
-void LinkSymbolsVisitor::Visit(FunctionDeclaration* node) {
-  abstract_types_.EnterContext();
-  for (auto& parameter : node->parameters) {
-    Visitor::Visit(parameter.get());
-    abstract_types_.DefineType(parameter->type, parameter->type_graph_id_);
-  }
-  Visitor::Visit(node->type.get());
-  abstract_types_.ExitContext();
-}
-
-void LinkSymbolsVisitor::Visit(FunctionDefinitionStatement* node) {
-  abstract_types_.EnterContext();
-  Visit(node->definition.get());
-  Visitor::Visit(node->value);
-  abstract_types_.ExitContext();
-}
-
-void LinkSymbolsVisitor::Visit(TypeDefinitionStatement* node) {
-  abstract_types_.EnterContext();
-  Visit(node->definition.get());
-  Visitor::Visit(node->value);
-  abstract_types_.ExitContext();
-}
-
-void LinkSymbolsVisitor::Visit(AbstractTypeDefinitionStatement* node) {
-  Visitor::Visit(node->type.get());
-  // TODO: can't be used before definition
-  abstract_types_.DefineType(node->type->type, node->type->type_graph_id_);
-}
-
-void LinkSymbolsVisitor::Visit(TypeclassDefinitionStatement* node) {
-  abstract_types_.EnterContext();
-  Visit(node->definition.get());
-  for (auto& requirement : node->requirements) {
-    Visit(requirement.get());
-  }
-  abstract_types_.ExitContext();
-}
-
-// Definition parts
-
-void LinkSymbolsVisitor::Visit(FunctionDefinition* node) {
-  for (auto& parameter : node->parameters) {
-    Visitor::Visit(parameter.get());
-    abstract_types_.DefineType(parameter->type, parameter->type_graph_id_);
-  }
-}
-
-void LinkSymbolsVisitor::Visit(TypeDefinition* node) {
-  Visitor::Visit(node->type.get());
-  for (auto& parameter : node->parameters) {
-    Visitor::Visit(parameter.get());
-    abstract_types_.DefineType(parameter->type, parameter->type_graph_id_);
-  }
-}
-
-// Flow control -----------------
-
-// Statements, expressions, blocks, etc. -----------------
-
-// Operators
-
-// Other Expressions
-
-// TODO: move to find_symbols_visitor
-void LinkSymbolsVisitor::Visit(LambdaFunction* node) {
-  abstract_types_.EnterContext();
-  for (auto& parameter : node->parameters) {
-    Visitor::Visit(parameter.get());
-    abstract_types_.DefineType(parameter->type, parameter->type_graph_id_);
-  }
-
-  ////////////
-  node->argument_graph_ids_.resize(node->arguments.size());
-  for (size_t i = 0; i < node->arguments.size(); ++i) {
-    node->argument_graph_ids_[i] = namespace_visitor_.GetAbstractTypeGraph()->AddVertex();
-  }
-
-  node->return_type_graph_id_ = namespace_visitor_.GetAbstractTypeGraph()->AddVertex();
-  ///////////
-
-  Visitor::Visit(node->expression);
-  abstract_types_.ExitContext();
-}
-
-// Name
-
 // Type, typeclass, etc. -----------------
 
 // Type
 
-void LinkSymbolsVisitor::Visit(TypeExpression* node) {
+// TODO: link internal stages
+void LinkSymbolsVisitor::Visit(TypeExpression* node) { // TODO: check
   std::vector<std::string> path;
-  path.reserve(node->namespaces.size());
+  path.reserve(node->path.size());
 
-  for (auto& type_namespace : node->namespaces) {
-    Visitor::Visit(type_namespace);
-    if (std::holds_alternative<std::unique_ptr<std::string>>(type_namespace)) {
-      path.push_back(*std::get<std::unique_ptr<std::string>>(type_namespace));
-    } else if (std::holds_alternative<std::unique_ptr<ParametrizedType>>(type_namespace)) {
-      path.push_back(std::get<std::unique_ptr<ParametrizedType>>(type_namespace)->type_expression->type);
-    } else {
-      // error
-    }
+  for (auto& path_type : node->path) {
+    path.push_back(NameFromTypeSubExpression(path_type));
   }
 
-  std::optional<utils::IdType> maybe_type = namespace_visitor_.FindType(path, node->type);
-  std::optional<utils::IdType> maybe_abstract_type = std::nullopt;
+  std::optional<utils::IdType> maybe_type = namespace_visitor_.FindType(path, NameFromTypeSubExpression(node->type));
 
-  if (path.size() == 0) {
-    maybe_abstract_type = abstract_types_.GetTypeId(node->type);
-  }
-
-  if (maybe_abstract_type.has_value()) {
-    if (maybe_type.has_value()) {
-      error_handling::HandleTypecheckError("Ambigious type");
-    } else {
-      node->type_id_ = maybe_abstract_type.value();
-    }
-  } else if (maybe_type.has_value()) {
+  if (maybe_type.has_value()) {
     node->type_id_ = maybe_type.value();
   } else {
     error_handling::HandleTypecheckError("Type not found");
@@ -193,36 +63,21 @@ void LinkSymbolsVisitor::Visit(TypeExpression* node) {
 
 // Typeclass
 
-void LinkSymbolsVisitor::Visit(TypeclassExpression* node) {
-  std::vector<std::string> path;
-  path.reserve(node->namespaces.size());
+void LinkSymbolsVisitor::Visit(TypeclassExpression* node) { // TODO: check
+  std::string typeclass;
 
-  for (auto& typeclass_namespace : node->namespaces) {
-    Visitor::Visit(typeclass_namespace);
-    if (std::holds_alternative<std::unique_ptr<std::string>>(typeclass_namespace)) {
-      path.push_back(*std::get<std::unique_ptr<std::string>>(typeclass_namespace));
-    } else if (std::holds_alternative<std::unique_ptr<ParametrizedType>>(typeclass_namespace)) {
-      path.push_back(std::get<std::unique_ptr<ParametrizedType>>(typeclass_namespace)->type_expression->type);
-    } else {
-      // error
-    }
+  if (std::holds_alternative<std::unique_ptr<std::string>>(node->typeclass)) {
+    typeclass = *std::get<std::unique_ptr<std::string>>(node->typeclass);
+  } else if (std::holds_alternative<std::unique_ptr<ParametrizedTypeclass>>(node->typeclass)) {
+    typeclass = std::get<std::unique_ptr<ParametrizedTypeclass>>(node->typeclass)->typeclass;
+  } else {
+    // error
   }
 
-  std::optional<utils::IdType> maybe_typeclass = namespace_visitor_.FindType(path, node->typeclass);
-  std::optional<utils::IdType> maybe_abstract_typeclass = std::nullopt;
+  std::optional<utils::IdType> maybe_typeclass = namespace_visitor_.FindTypeclass(typeclass);
 
-  if (path.size() == 0) {
-    maybe_abstract_typeclass = abstract_types_.GetTypeId(node->typeclass);
-  }
-
-  if (maybe_abstract_typeclass.has_value()) {
-    if (maybe_typeclass.has_value()) {
-      error_handling::HandleTypecheckError("Ambigious type");
-    } else {
-      node->type_id_ = maybe_abstract_typeclass.value();
-    }
-  } else if (maybe_typeclass.has_value()) {
-    node->type_id_ = maybe_typeclass.value();
+  if (maybe_typeclass.has_value()) {
+    node->typeclass_id_ = maybe_typeclass.value();
   } else {
     error_handling::HandleTypecheckError("Type not found");
   }
diff --git a/src/type_check_visitor.cpp b/src/type_check_visitor.cpp
index da56801..2928723 100644
--- a/src/type_check_visitor.cpp
+++ b/src/type_check_visitor.cpp
@@ -12,44 +12,47 @@ namespace interpreter {
 // Sources -----------------
 
 void TypeCheckVisitor::Visit(SourceFile* node) {
-  for (auto& statement : node->statements) {
-    if (std::holds_alternative<Partition>(statement)) {
-      Visit(&std::get<Partition>(statement));
-    } else if (std::holds_alternative<SourceStatement>(statement)) {
-      Visitor::Visit(std::get<SourceStatement>(statement));
-    } else {
-      // error
-    }
-  }
-
-  current_type_ = context_manager_.AddType(info::type::InternalType::Unit);
-}
-
-void TypeCheckVisitor::Visit(Sources* node) {
   for (auto& statement : node->statements) {
     Visitor::Visit(statement);
   }
+
   current_type_ = context_manager_.AddType(info::type::InternalType::Unit);
 }
 
 // Namespaces, partitions -----------------
 
+void TypeCheckVisitor::Visit(PartitionSources* node) {
+  for (auto& statement : node->statements) {
+    Visitor::Visit(statement);
+  }
+
+  current_type_ = context_manager_.AddType(info::type::InternalType::Unit);
+}
+
 void TypeCheckVisitor::Visit(Partition* node) {
-  Visit(node->scope.get());
+  Visit(&node->scope);
+
+  current_type_ = context_manager_.AddType(info::type::InternalType::Unit);
+}
+
+void TypeCheckVisitor::Visit(NamespaceSources* node) {
+  for (auto& statement : node->statements) {
+    Visitor::Visit(statement);
+  }
 
   current_type_ = context_manager_.AddType(info::type::InternalType::Unit);
 }
 
 void TypeCheckVisitor::Visit(Namespace* node) {
-  if (node->name.has_value()) {
-    // TODO: add modifiers
-    context_manager_.EnterVariableContext(node->name.value().name,
-      context_manager_.AddType(info::type::DefinedType {node->type_id_.value()}));
+  if (node->modifier.has_value()) {
+    // TODO
+    // context_manager_.EnterVariableContext(node->name.value().name,
+    //  context_manager_.AddType(info::type::DefinedType {node->type_id_.value()}));
   }
 
   namespace_visitor_.EnterNamespace(node->type);
 
-  Visit(node->scope.get());
+  Visit(&node->scope);
 
   namespace_visitor_.ExitNamespace();
 
@@ -89,15 +92,24 @@ void TypeCheckVisitor::Visit(FunctionDefinitionStatement* node) {
   // check, that all paramaters used ??
   context_manager_.EnterContext();
 
+  info::definition::Function* function_info = namespace_visitor_.GetGlobalInfo()->GetFunctionInfo(node->function_id_);
+
+  if (!function_info->declaration.has_value()) {
+    error_handling::HandleTypecheckError("Function defined, but not declared");
+  }
+
+  info::definition::FunctionDeclaration& declaration = function_info->declaration.value();
+
+  declaration.parameters
+
   // Visit(node->definition.get()); // ??
   for (size_t i = 0; i < node->definition->arguments.size(); ++i) {
     context_manager_.DefineVariable(node->definition->arguments[i].name,
-      context_manager_.AddType(info::type::AbstractType { node->argument_graph_ids_[i] }));
+      declaration.argument_types[i]);
   }
 
   Visitor::Visit(node->value);
-  context_manager_.EqualTypes(
-    context_manager_.AddType(info::type::AbstractType { node->return_type_graph_id_ }), current_type_);
+  context_manager_.EqualTypes(declaration.argument_types.back(), current_type_);  // return type ??
 
   context_manager_.ExitContext();
 
@@ -113,7 +125,7 @@ void TypeCheckVisitor::Visit(TypeDefinitionStatement* node) {
 }
 
 void TypeCheckVisitor::Visit(AbstractTypeDefinitionStatement* node) {
-  utils::IdType type = context_manager_.AddType(info::type::AbstractType {node->type_graph_id_} );
+  utils::IdType type = context_manager_.AddType(info::type::DefinedType );
 
   // Visit(node->type.get()); ??
   for (auto& typeclass : node->type->typeclasses) { // TODO
@@ -680,9 +692,25 @@ void TypeCheckVisitor::Visit(ExtendedScopedAnyType* node) {
 
 // Typeclass
 
-void TypeCheckVisitor::Visit(ParametrizedTypeclass* node) {}
+void Visitor::Visit(TypeclassExpression* node) {
+  Visit(node->typeclass);
+}
 
-void TypeCheckVisitor::Visit(TypeclassExpression* node) {}
+void Visitor::Visit(ParametrizedTypeclass* node) {
+  Visit(&node->typeclass);
+  for (auto& parameter : node->parameters) {
+    Visit(parameter.get());
+  }
+}
+
+// Typeclass & Type -----------------
+
+void Visitor::Visit(ParametrizedType* node) {
+  Visit(&node->type);
+  for (auto& parameter : node->parameters) {
+    Visit(parameter.get());
+  }
+}
 
 // Identifiers, constants, etc. -----------------
 
diff --git a/src/types.cpp b/src/types.cpp
new file mode 100644
index 0000000..18e8a1a
--- /dev/null
+++ b/src/types.cpp
@@ -0,0 +1,275 @@
+// for clangd
+#include "../include/types.hpp"
+
+namespace info::type {
+
+bool AbstractType::Same(const AbstractType& type) const {
+  return name_ == type.name_;
+}
+
+bool AbstractType::operator<(const AbstractType& type) const {
+  for (auto& typeclass : requirements_) {
+    if (type.requirements_.count(typeclass) == 0) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool AbstractType::operator>(const AbstractType& type) const {
+  return type < *this;
+}
+
+//
+
+bool DefinedType::Same(const DefinedType& type) const {
+  return type_id_ == type.type_id_
+    && type_manager_->GetAnyType(type_).value()->Same(*type_manager_->GetAnyType(type.type_).value());
+}
+
+bool DefinedType::operator<(const DefinedType& type) const {
+  return type_id_ == type.type_id_
+    && *type_manager_->GetAnyType(type_).value() < *type_manager_->GetAnyType(type.type_).value();
+}
+
+bool DefinedType::operator>(const DefinedType& type) const {
+  return type < *this;
+}
+
+//
+
+bool TupleType::Same(const TupleType& type) const {
+  if (fields_.size() != type.fields_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < fields_.size(); ++i) {
+    if (!type_manager_->GetAnyType(fields_[i].second).value()->Same(*type_manager_->GetAnyType(type.fields_[i].second).value())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool TupleType::operator<(const TupleType& type) const {
+  if (fields_.size() != type.fields_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < fields_.size(); ++i) {
+    if (!(*type_manager_->GetAnyType(fields_[i].second).value() < *type_manager_->GetAnyType(type.fields_[i].second).value())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool TupleType::operator>(const TupleType& type) const {
+  return type < *this;
+}
+
+//
+
+bool VariantType::Same(const VariantType& type) const {
+  if (constructors_.size() != type.constructors_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < constructors_.size(); ++i) {
+    if (!constructors_[i].Same(constructors_[i])) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool VariantType::operator<(const VariantType& type) const {
+  if (constructors_.size() != type.constructors_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < constructors_.size(); ++i) {
+    if (!(constructors_[i] < constructors_[i])) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool VariantType::operator>(const VariantType& type) const {
+  return type < *this;
+}
+
+//
+
+bool OptionalType::Same(const OptionalType& type) const {
+  return type_manager_->GetAnyType(type_).value()->Same(*type_manager_->GetAnyType(type.type_).value());
+}
+
+bool OptionalType::operator<(const OptionalType& type) const {
+  return *type_manager_->GetAnyType(type_).value() < *type_manager_->GetAnyType(type.type_).value();
+}
+
+bool OptionalType::operator>(const OptionalType& type) const {
+  return type < *this;
+}
+
+//
+
+bool ReferenceToType::Same(const ReferenceToType& type) const {
+  return references_ == type.references_ && type_manager_->GetAnyType(type_).value()->Same(*type_manager_->GetAnyType(type.type_).value());
+}
+
+bool ReferenceToType::operator<(const ReferenceToType& type) const {
+  return references_ == type.references_ && *type_manager_->GetAnyType(type_).value() < *type_manager_->GetAnyType(type.type_).value();
+}
+
+bool ReferenceToType::operator>(const ReferenceToType& type) const {
+  return type < *this;
+}
+
+//
+
+bool FunctionType::Same(const FunctionType& type) const {
+  if (argument_types_.size() != type.argument_types_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < argument_types_.size(); ++i) {
+    if (!type_manager_->GetAnyType(argument_types_[i]).value()->Same(*type_manager_->GetAnyType(type.argument_types_[i]).value())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool FunctionType::operator<(const FunctionType& type) const {
+  if (argument_types_.size() != type.argument_types_.size()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < argument_types_.size(); ++i) {
+    if (!(*type_manager_->GetAnyType(argument_types_[i]).value() < *type_manager_->GetAnyType(type.argument_types_[i]).value())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool FunctionType::operator>(const FunctionType& type) const {
+  return type < *this;
+}
+
+//
+
+bool ArrayType::Same(const ArrayType& type) const {
+  return size_ == type.size_ && type_manager_->GetAnyType(elements_type_).value()->Same(*type_manager_->GetAnyType(type.elements_type_).value());
+}
+
+bool ArrayType::operator<(const ArrayType& type) const {
+  return size_ == type.size_ && *type_manager_->GetAnyType(elements_type_).value() < *type_manager_->GetAnyType(type.elements_type_).value();
+}
+
+bool ArrayType::operator>(const ArrayType& type) const {
+  return type < *this;
+}
+
+//
+
+bool Type::Same(const Type& type) const {
+  size_t this_index = type_.index();
+  size_t type_index = type.type_.index();
+
+  if (this_index == type_index) {
+    switch (this_index) {
+    case 0:
+      return std::get<AbstractType>(type_).Same(std::get<AbstractType>(type.type_));
+    case 1:
+      return std::get<DefinedType>(type_).Same(std::get<DefinedType>(type.type_));
+    case 2:
+      return std::get<InternalType>(type_) == std::get<InternalType>(type.type_);
+    case 3:
+      return std::get<TupleType>(type_).Same(std::get<TupleType>(type.type_));
+    case 4:
+      return std::get<VariantType>(type_).Same(std::get<VariantType>(type.type_));
+    case 5:
+      return std::get<ReferenceToType>(type_).Same(std::get<ReferenceToType>(type.type_));
+    case 6:
+      return std::get<FunctionType>(type_).Same(std::get<FunctionType>(type.type_));
+    case 7:
+      return std::get<ArrayType>(type_).Same(std::get<ArrayType>(type.type_));
+    default:
+      // error
+      break;
+    }
+  }
+
+  return false;
+} // some rule exceptions ??
+
+bool Type::operator<(const Type& type) const {
+  size_t this_index = type_.index();
+  size_t type_index = type.type_.index();
+
+  if (this_index == type_index) {
+    switch (this_index) {
+    case 0:
+      return std::get<AbstractType>(type_) < std::get<AbstractType>(type.type_);
+    case 1:
+      return std::get<DefinedType>(type_) < std::get<DefinedType>(type.type_);
+    case 2:
+      return std::get<InternalType>(type_) == std::get<InternalType>(type.type_);
+    case 3:
+      return std::get<TupleType>(type_) < std::get<TupleType>(type.type_);
+    case 4:
+      return std::get<VariantType>(type_) < std::get<VariantType>(type.type_);
+    case 5:
+      return std::get<ReferenceToType>(type_) < std::get<ReferenceToType>(type.type_);
+    case 6:
+      return std::get<FunctionType>(type_) < std::get<FunctionType>(type.type_);
+    case 7:
+      return std::get<ArrayType>(type_) < std::get<ArrayType>(type.type_);
+    default:
+      // error
+      break;
+    }
+  }
+
+  return false;
+} // TODO: some rule exceptions ??
+
+bool Type::operator>(const Type& type) const {
+  return type < *this;
+}
+
+//
+
+template<typename T>
+utils::IdType TypeManager::AddType(const T&& type) {
+  types_.emplace_back(std::forward(type));
+  return types_.size() - 1;
+}
+
+template<typename T>
+std::optional<T*> TypeManager::GetType(utils::IdType type_id) {
+  if (!std::holds_alternative<T>(types_.at(type_id))) {
+    return std::nullopt;
+  }
+  return &std::get<T>(types_.at(type_id));
+}
+
+std::optional<Type*> TypeManager::GetAnyType(utils::IdType type_id) {
+  return &types_.at(type_id);
+}
+
+void TypeManager::AddTypeRequirement(utils::IdType type, utils::IdType requrement) {} // TODO
+void TypeManager::EqualTypes(utils::IdType first_type, utils::IdType second_type) {} // TODO
+
+} // namespace info::type
+