diff --git a/include/definitions.hpp b/include/definitions.hpp
index 2f09f23..cfe6c68 100644
--- a/include/definitions.hpp
+++ b/include/definitions.hpp
@@ -79,8 +79,7 @@ struct Function {
 
 struct Typeclass {
   std::vector<Parameter> parameters;
-  std::vector<FunctionDeclaration> function_requirements;
-  std::vector<FunctionDeclaration> method_requirements;
+  interpreter::tokens::TypeclassDefinitionStatement* node;
 };
 
 struct Import {
diff --git a/include/error_handling.hpp b/include/error_handling.hpp
index d99e443..7b53ab1 100644
--- a/include/error_handling.hpp
+++ b/include/error_handling.hpp
@@ -23,38 +23,36 @@ inline void PrintPosition(std::ostream& out,
 inline void HandleParsingError(const std::string& message,
                                std::pair<size_t, size_t> start_position,
                                std::pair<size_t, size_t> end_position) {
-  std::cout << "Parsing Error: " << message << " at ";
+  std::cout << "\x1b[1;31mParsing Error:\x1b[0m " << message << " at ";
   PrintPosition(std::cout, start_position, end_position);
   std::cout << ".\n";
   exit(1);
 }
 
 inline void HandleGeneralError(const std::string& message) {
-  std::cout << "General Error: " << message << ".\n";
+  std::cout << "\x1b[1;31mGeneral Error:\x1b[0m " << message << ".\n";
   exit(1);
 }
 
 inline void HandleInternalError(const std::string& message, const std::string& place) {
-  std::cout << "Internal Error: " << message << " at " << place << ".\n";
+  std::cout << "\x1b[1;31mInternal Error:\x1b[0m " << message << " at " << place << ".\n";
   exit(1);
 }
 
 inline void HandleTypecheckError(const std::string& message,
-                                 const interpreter::tokens::BaseNode& node) { // TODO: place in code
-  std::cout << "Typecheck Error: " << message << " at ";
+                                 const interpreter::tokens::BaseNode& node) {
+  std::cout << "\x1b[1;31mTypecheck Error:\x1b[0m " << message << " at ";
   PrintPosition(std::cout, node.start_position, node.end_position);
   std::cout << ".\n";
   exit(1);
 }
 
 inline void HandleRuntimeError(const std::string& message,
-                                 const interpreter::tokens::BaseNode& node) { // TODO: place in code
-  std::cout << "Runtime Error: " << message << " at ";
+                                 const interpreter::tokens::BaseNode& node) {
+  std::cout << "\x1b[1;31mRuntime Error:\x1b[0m " << message << " at ";
   PrintPosition(std::cout, node.start_position, node.end_position);
   std::cout << ".\n";
   exit(1);
 }
 
-// ...
-
 } // namespace error_handling
diff --git a/include/execute_visitor.hpp b/include/execute_visitor.hpp
index e9340dc..b3a3057 100644
--- a/include/execute_visitor.hpp
+++ b/include/execute_visitor.hpp
@@ -165,7 +165,7 @@ private:
 
   utils::IdType current_value_;
   std::optional<LoopControlExpression> active_loop_control_expression_;
-  std::optional<utils::IdType> return_value_; // TODO: work outside block ??
+  std::optional<utils::IdType> returned_value_; // TODO: work outside block ??
   std::optional<utils::IsConstModifier> is_const_definition_;
   bool case_matched_;
 };
diff --git a/include/find_symbols_visitor.hpp b/include/find_symbols_visitor.hpp
index 625fb6b..a5eeb17 100644
--- a/include/find_symbols_visitor.hpp
+++ b/include/find_symbols_visitor.hpp
@@ -121,7 +121,6 @@ private:
 private:
   info::GlobalInfo::NamespaceVisitor namespace_visitor_;
 
-  bool is_in_statement_ = false;
   std::any current_info_;
 };
 
diff --git a/include/global_info.hpp b/include/global_info.hpp
index d61cfdd..7b34aa0 100644
--- a/include/global_info.hpp
+++ b/include/global_info.hpp
@@ -51,10 +51,12 @@ public:
     void ToGlobalNamespace();
 
     utils::IdType AddFunctionDeclaration(const std::string& name,
-                                         definition::FunctionDeclaration&& function_declaration_info);
+                                         definition::FunctionDeclaration&& function_declaration_info,
+                                         const interpreter::tokens::BaseNode& base_node);
 
     utils::IdType AddFunctionDefinition(const std::string& name,
-                                        definition::FunctionDefinition&& function_definition_info);
+                                        definition::FunctionDefinition&& function_definition_info,
+                                        const interpreter::tokens::BaseNode& base_node);
 
     utils::IdType AddType(const std::string& type,
                           definition::Type&& type_info,
@@ -124,6 +126,10 @@ public:
     std::optional<utils::IdType> FindNamespaceIn(
       utils::IdType current_namespace,
       const std::vector<std::string>& path);
+
+    std::unordered_map<std::string, utils::IdType>*
+      ChooseNamespaces(std::optional<utils::IsConstModifier> modifier,
+                       utils::IdType namespace_id);
   private:
     GlobalInfo& global_info_;
 
@@ -135,7 +141,6 @@ public:
     return NamespaceVisitor(*this);
   }
 
-  // remember about vector realloc
   definition::Function& GetFunctionInfo(utils::IdType id) {
     return functions_.at(id);
   }
@@ -148,27 +153,22 @@ public:
     return &std::get<T>(types_[id].type);
   }
 
-  // remember about vector realloc
   definition::Type& GetAnyTypeInfo(utils::IdType id) {
     return types_.at(id);
   }
 
-  // remember about vector realloc
   definition::Typeclass& GetTypeclassInfo(utils::IdType id) {
     return typeclasses_.at(id);
   }
 
-  // remember about vector realloc
   definition::Constructor& GetConstructorInfo(utils::IdType id) {
     return constructors_.at(id);
   }
 
-  // remember about vector realloc
   definition::Namespace& GetNamespaceInfo(utils::IdType id) {
     return namespaces_.at(id);
   }
 
-  // remember about vector realloc
   PartitionInfo& GetPartitionInfo(utils::IdType id) {
     return partitions_.at(id);
   }
diff --git a/src/build_visitor.cpp b/src/build_visitor.cpp
index 179dfd1..367726a 100644
--- a/src/build_visitor.cpp
+++ b/src/build_visitor.cpp
@@ -1,5 +1,3 @@
-#include <iostream>
-
 #include <memory>
 #include <variant>
 
@@ -63,6 +61,8 @@ void BuildVisitor::Visit(Namespace* node) {
       node->modifier = utils::IsConstModifier::Const;
     } else if (modifier == "var") {
       node->modifier = utils::IsConstModifier::Var;
+    } else {
+      error_handling::HandleInternalError("Can't parse namespace modifier", "BuildVisitor.Namespace");
     }
   }
 
@@ -150,6 +150,8 @@ void BuildVisitor::Visit(VariableDefinitionStatement* node) {
     node->modifier = utils::IsConstModifier::Const;
   } else if (modifier == "var") {
     node->modifier = utils::IsConstModifier::Var;
+  } else {
+    // error
   }
 
   current_node_ = parse_node.ChildByFieldName("name");
@@ -163,6 +165,8 @@ void BuildVisitor::Visit(VariableDefinitionStatement* node) {
     node->assignment_modifier = utils::AssignmentModifier::Assign;
   } else if (assignment_modifier == "<-") {
     node->assignment_modifier = utils::AssignmentModifier::Move;
+  } else {
+    // error
   }
 
   current_node_ = parse_node;
diff --git a/src/execute_visitor.cpp b/src/execute_visitor.cpp
index 9b4aed5..afba6ce 100644
--- a/src/execute_visitor.cpp
+++ b/src/execute_visitor.cpp
@@ -131,14 +131,18 @@ void ExecuteVisitor::Visit(Match* node) {
     context_manager_.ExitContext();
   }
 
-  if (statement_visited) {
-    current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
-          info::value::OptionalValue(current_value_, context_manager_.GetValueManager()),
-          utils::ValueType::Tmp);
-  } else {
-    current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
-          info::value::OptionalValue(std::nullopt, context_manager_.GetValueManager()),
-          utils::ValueType::Tmp);
+  // --- instead of optional return value or throw runtime error ---
+  // if (statement_visited) {
+  //   current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
+  //         info::value::OptionalValue(current_value_, context_manager_.GetValueManager()),
+  //         utils::ValueType::Tmp);
+  // } else {
+  //   current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
+  //         info::value::OptionalValue(std::nullopt, context_manager_.GetValueManager()),
+  //         utils::ValueType::Tmp);
+  // }
+  if (!statement_visited) {
+    error_handling::HandleRuntimeError("Value match option not found", node->base);
   }
 
   context_manager_.ExitContext();
@@ -283,10 +287,11 @@ void ExecuteVisitor::Visit(Block* node) {
   context_manager_.EnterContext();
 
   for (auto& statement : node->statements) {
-    return_value_ = std::nullopt;
+    returned_value_ = std::nullopt;
     Visitor::Visit(statement);
-    if (return_value_.has_value()) {
-      current_value_ = return_value_.value();
+    if (returned_value_.has_value()) {
+      current_value_ = returned_value_.value();
+      returned_value_ = std::nullopt; // ??
       return;
     }
   }
@@ -457,7 +462,7 @@ void ExecuteVisitor::Visit(VariantExpression* node) {
 
 void ExecuteVisitor::Visit(ReturnExpression* node) {
   Visitor::Visit(node->expression);
-  return_value_ = current_value_;
+  returned_value_ = current_value_;
 }
 
 
diff --git a/src/find_symbols_visitor.cpp b/src/find_symbols_visitor.cpp
index 537b0b2..2273a82 100644
--- a/src/find_symbols_visitor.cpp
+++ b/src/find_symbols_visitor.cpp
@@ -1,3 +1,5 @@
+#include <iostream>
+
 // for clangd
 #include "../include/find_symbols_visitor.hpp"
 
@@ -8,7 +10,7 @@ namespace interpreter {
 // Namespaces, partitions -----------------
 
 void FindSymbolsVisitor::Visit(Namespace* node) {
-  namespace_visitor_.AddEnterNamespace(node->type, node->modifier, node->base);
+   namespace_visitor_.AddEnterNamespace(node->type, node->modifier, node->base);
 
   Visitor::Visit(&node->scope);
 
@@ -19,27 +21,19 @@ void FindSymbolsVisitor::Visit(Namespace* node) {
 
 // TODO: add imported symbols to symbol table (global info)
 void FindSymbolsVisitor::Visit(ImportStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::Import info;
   info.module_name = node->module_name;
   info.symbols = node->symbols;
   namespace_visitor_.AddImport(std::move(info), node->name);
-
-  is_in_statement_ = false;
 }
 
 void FindSymbolsVisitor::Visit(AliasDefinitionStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::Type info;
 
   info::definition::AliasType alias_info;
 
   alias_info.modifier = node->modifier;
 
-  // TODO: deduce parameter requirements
-
   alias_info.parameters = node->parameters;
   alias_info.value.node = node->value.get();
   alias_info.node = node;
@@ -47,14 +41,9 @@ void FindSymbolsVisitor::Visit(AliasDefinitionStatement* node) {
   info.type = std::move(alias_info);
 
   node->type_id_ = namespace_visitor_.AddType(node->type, std::move(info), node->base);
-
-  is_in_statement_ = false;
 }
 
 void FindSymbolsVisitor::Visit(FunctionDeclaration* node) {
-  bool was_in_statement = is_in_statement_;
-  is_in_statement_ = true;
-
   info::definition::FunctionDeclaration info;
 
   info.parameters.resize(node->parameters.size());
@@ -71,17 +60,10 @@ void FindSymbolsVisitor::Visit(FunctionDeclaration* node) {
 
   info.node = node;
 
-  if (was_in_statement) {
-    current_info_ = std::move(info);
-  } else {
-    node->function_id_ = namespace_visitor_.AddFunctionDeclaration(node->name, std::move(info));
-    is_in_statement_ = false;
-  }
+  node->function_id_ = namespace_visitor_.AddFunctionDeclaration(node->name, std::move(info), node->base);
 }
 
 void FindSymbolsVisitor::Visit(FunctionDefinitionStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::FunctionDefinition info;
 
   auto definition = node->definition.get();
@@ -93,14 +75,10 @@ void FindSymbolsVisitor::Visit(FunctionDefinitionStatement* node) {
 
   info.node = node;
 
-  node->function_id_ = namespace_visitor_.AddFunctionDefinition(definition->name, std::move(info));
-
-  is_in_statement_ = false;
+  node->function_id_ = namespace_visitor_.AddFunctionDefinition(definition->name, std::move(info), node->base);
 }
 
 void FindSymbolsVisitor::Visit(TypeDefinitionStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::Type info;
 
   auto definition = node->definition.get();
@@ -127,13 +105,9 @@ void FindSymbolsVisitor::Visit(TypeDefinitionStatement* node) {
   info.type = std::move(any_type_info);
 
   node->type_id_ = namespace_visitor_.AddType(type, std::move(info), node->base);
-
-  is_in_statement_ = false;
 }
 
 void FindSymbolsVisitor::Visit(AbstractTypeDefinitionStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::AbstractType info;
 
   Visit(node->type.get());
@@ -145,17 +119,15 @@ void FindSymbolsVisitor::Visit(AbstractTypeDefinitionStatement* node) {
   std::string type = info.type.type;
 
   node->type_id_ = namespace_visitor_.AddAbstractType(type, std::move(info), node->base);
-
-  is_in_statement_ = false;
 }
 
 void FindSymbolsVisitor::Visit(TypeclassDefinitionStatement* node) {
-  is_in_statement_ = true;
-
   info::definition::Typeclass info;
 
   auto definition = node->definition.get();
 
+  std::string& type_name = definition->type.get()->type;
+
   info.parameters.resize(definition->parameters.size());
   for (size_t i = 0; i < definition->parameters.size(); ++i) {
     Visit(definition->parameters[i].get());
@@ -163,32 +135,25 @@ void FindSymbolsVisitor::Visit(TypeclassDefinitionStatement* node) {
     current_info_.reset();
   }
 
-  info.function_requirements.resize(node->function_requirements.size());
+  namespace_visitor_.AddEnterNamespace(type_name, std::nullopt, node->base);
   for (size_t i = 0; i < node->function_requirements.size(); ++i) {
     Visit(node->function_requirements[i].get());
-    info.function_requirements[i] = std::move(std::any_cast<info::definition::FunctionDeclaration>(current_info_));
-    current_info_.reset();
   }
+  namespace_visitor_.ExitNamespace();
 
-  info.method_requirements.resize(node->method_requirements.size());
+  namespace_visitor_.AddEnterNamespace(type_name, utils::IsConstModifier::Var, node->base);
   for (size_t i = 0; i < node->method_requirements.size(); ++i) {
     Visit(node->method_requirements[i].get());
-    info.method_requirements[i] = std::move(std::any_cast<info::definition::FunctionDeclaration>(current_info_));
-    current_info_.reset();
   }
+  namespace_visitor_.ExitNamespace();
 
-  node->typeclass_id_ = namespace_visitor_.AddTypeclass(definition->type.get()->type, std::move(info), node->base);
+  info.node = node;
 
-  is_in_statement_ = false;
+  node->typeclass_id_ = namespace_visitor_.AddTypeclass(type_name, std::move(info), node->base);
 }
 
 void FindSymbolsVisitor::Visit(PartitionStatement* node) {
-  is_in_statement_ = true;
-
   node->executable_id_ = namespace_visitor_.AddPartition(node->name.path, node);
-  // TODO: typecheck error on same tests
-
-  is_in_statement_ = false;
 }
 
 // Definition parts
diff --git a/src/global_info.cpp b/src/global_info.cpp
index 361c6e5..766dd30 100644
--- a/src/global_info.cpp
+++ b/src/global_info.cpp
@@ -24,20 +24,22 @@ void GlobalInfo::NamespaceVisitor::AddEnterNamespace(const std::string& name,
     error_handling::HandleTypecheckError("Can't define basic type namespace", base_node);
   }
 
-  size_t id = global_info_.namespaces_.size();
-  global_info_.namespaces_.emplace_back();
-  definition::Namespace* namespace_info = &global_info_.namespaces_.back();
+  auto current_namespaces = ChooseNamespaces(modifier, namespace_stack_.back());
+
+  utils::IdType id = 0;
+
+  auto namespace_iter = current_namespaces->find(name);
+  if (namespace_iter == current_namespaces->end()) {
+    id = global_info_.namespaces_.size();
+    (*current_namespaces)[name] = id;
+    global_info_.namespaces_.emplace_back();
+  } else {
+    id = namespace_iter->second;
+  }
+  definition::Namespace* namespace_info = &global_info_.namespaces_[id];
 
   if (modifier.has_value()) {
-    if (modifier.value() == utils::IsConstModifier::Const) {
-      global_info_.namespaces_[namespace_stack_.back()].const_namespaces[name] = id;
-    } else {
-      global_info_.namespaces_[namespace_stack_.back()].var_namespaces[name] = id;
-    }
-
     namespace_info->modifier = modifier;
-  } else {
-    global_info_.namespaces_[namespace_stack_.back()].namespaces[name] = id;
   }
 
   namespace_info->parent_namespace = namespace_stack_.back();
@@ -48,36 +50,15 @@ void GlobalInfo::NamespaceVisitor::AddEnterNamespace(const std::string& name,
   current_path_.push_back(name);
 }
 
-// better code ??
 void GlobalInfo::NamespaceVisitor::EnterNamespace(const std::string& name,
                                                   std::optional<utils::IsConstModifier> modifier) {
-
-  if (!modifier.has_value()) {
-    for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
-      auto namespace_iter = global_info_.namespaces_[namespace_stack_[i]].namespaces.find(name);
-      if (namespace_iter != global_info_.namespaces_[namespace_stack_[i]].namespaces.end()) {
-        namespace_stack_.push_back(namespace_iter->second);
-        current_path_.push_back(name);
-        return;
-      }
-    }
-  } else if (modifier.has_value() && modifier.value() == utils::IsConstModifier::Const) {
-    for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
-    auto const_namespace_iter = global_info_.namespaces_[namespace_stack_[i]].const_namespaces.find(name);
-      if (const_namespace_iter != global_info_.namespaces_[namespace_stack_[i]].const_namespaces.end()) {
-        namespace_stack_.push_back(const_namespace_iter->second);
-        current_path_.push_back(name);
-        return;
-      }
-    }
-  } else {
-    for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
-    auto var_namespace_iter = global_info_.namespaces_[namespace_stack_[i]].var_namespaces.find(name);
-      if (var_namespace_iter != global_info_.namespaces_[namespace_stack_[i]].var_namespaces.end()) {
-        namespace_stack_.push_back(var_namespace_iter->second);
-        current_path_.push_back(name);
-        return;
-      }
+  for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
+    auto current_namespaces = ChooseNamespaces(modifier, i);
+    auto namespace_iter = current_namespaces->find(name);
+    if (namespace_iter != current_namespaces->end()) {
+      namespace_stack_.push_back(namespace_iter->second);
+      current_path_.push_back(name);
+      return;
     }
   }
 
@@ -104,51 +85,56 @@ void GlobalInfo::NamespaceVisitor::ToGlobalNamespace() {
 }
 
 utils::IdType GlobalInfo::NamespaceVisitor::AddFunctionDeclaration(
-  const std::string& name,
-  definition::FunctionDeclaration&& function_declaration_info) {
-
-  size_t id = 0;
+    const std::string& name,
+    definition::FunctionDeclaration&& function_declaration_info,
+    const interpreter::tokens::BaseNode& base_node) {
+  utils::IdType id = 0;
 
   auto function_id_iter = global_info_.namespaces_[namespace_stack_.back()].functions.find(name);
-
   if (function_id_iter == global_info_.namespaces_[namespace_stack_.back()].functions.end()) {
     id = global_info_.functions_.size();
     global_info_.namespaces_[namespace_stack_.back()].functions[name] = id;
     global_info_.functions_.emplace_back();
     global_info_.functions_.back().argument_count = function_declaration_info.argument_types.size(); // add return type
-    global_info_.functions_.back().declaration = std::move(function_declaration_info);
   } else {
     id = function_id_iter->second;
-    if (global_info_.functions_.back().argument_count != function_declaration_info.argument_types.size()) {
-      error_handling::HandleInternalError("Not same argument count in function definition and declaration",
-                                          "GlobalInfo.NamespaceVisitor. AddFunctionDeclaration");
+    if (global_info_.functions_[id].argument_count != function_declaration_info.argument_types.size()) {
+      error_handling::HandleTypecheckError("Function declaration: not same argument count in function definition and declaration", base_node);
     }
-    global_info_.functions_[id].declaration = std::move(function_declaration_info);
   }
 
+  if (global_info_.functions_[id].declaration.has_value()) {
+    error_handling::HandleTypecheckError("Second function declaration", base_node);
+  }
+  global_info_.functions_[id].declaration = std::move(function_declaration_info);
+
   return id;
 }
 
-utils::IdType GlobalInfo::NamespaceVisitor::AddFunctionDefinition(const std::string& name,
-    definition::FunctionDefinition&& function_definition_info) {
-  size_t id = 0;
+utils::IdType GlobalInfo::NamespaceVisitor::AddFunctionDefinition(
+    const std::string& name,
+    definition::FunctionDefinition&& function_definition_info,
+    const interpreter::tokens::BaseNode& base_node) {
+  utils::IdType id = 0;
 
   auto function_id_iter = global_info_.namespaces_[namespace_stack_.back()].functions.find(name);
-
   if (function_id_iter == global_info_.namespaces_[namespace_stack_.back()].functions.end()) {
     id = global_info_.functions_.size();
     global_info_.namespaces_[namespace_stack_.back()].functions[name] = id;
     global_info_.functions_.emplace_back();
     global_info_.functions_.back().argument_count = function_definition_info.argument_names.size() + 1;
-    global_info_.functions_.back().definition = std::move(function_definition_info);
   } else {
     id = function_id_iter->second;
-    if (global_info_.functions_.back().argument_count != function_definition_info.argument_names.size() + 1) {
-      error_handling::HandleInternalError("Not same argument count in function definition and declaration", "GlobalInfo");
+    if (global_info_.functions_[id].argument_count != function_definition_info.argument_names.size() + 1) {
+      error_handling::HandleTypecheckError("Function definition: not same argument count in function definition and declaration", base_node);
     }
-    global_info_.functions_[id].definition = std::move(function_definition_info);
   }
 
+  if (global_info_.functions_[id].definition.has_value()) {
+    error_handling::HandleTypecheckError("Second function definition", base_node);
+  }
+  global_info_.functions_[id].definition = std::move(function_definition_info);
+
   return id;
 }
 
@@ -161,7 +147,7 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddType(const std::string& type,
     error_handling::HandleTypecheckError("Can't redefine basic type", base_node);
   }
 
-  size_t id = 0;
+  utils::IdType id = 0;
 
   auto type_id_iter = global_info_.namespaces_[namespace_stack_.back()].types.find(type);
 
@@ -224,17 +210,16 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddAbstractType(const std::string& a
     error_handling::HandleTypecheckError("Can't redefine basic type as abstract type", base_node);
   }
 
-  if (!FindAbstractType(abstract_type).has_value()) {
-    utils::IdType id = global_info_.abstract_types_.size();
-    global_info_.name_to_abstract_type_[abstract_type] = id;
-    global_info_.abstract_types_.push_back(std::move(abstract_type_info));
-
-    return id;
+  if (FindAbstractType(abstract_type).has_value()) {
+    error_handling::HandleTypecheckError("More then one abstract type with the same name in namespace",
+                                         base_node);
   }
 
-  error_handling::HandleTypecheckError("More then one abstract type with the same name in namespace",
-                                       base_node);
-  return 0;
+  utils::IdType id = global_info_.abstract_types_.size();
+  global_info_.name_to_abstract_type_[abstract_type] = id;
+  global_info_.abstract_types_.push_back(std::move(abstract_type_info));
+
+  return id;
 }
 
 utils::IdType GlobalInfo::NamespaceVisitor::AddTypeclass(const std::string& typeclass,
@@ -244,17 +229,15 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddTypeclass(const std::string& type
     error_handling::HandleTypecheckError("Can't redefine basic type as typeclass", base_node);
   }
 
-  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));
-
-    return id;
+  if (FindTypeclass(typeclass).has_value()) {
+    error_handling::HandleTypecheckError("More then one typeclass with the same name in namespace", base_node);
   }
 
+  utils::IdType 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", base_node);
-  return 0;
+  return id;
 }
 
 utils::IdType GlobalInfo::NamespaceVisitor::AddConstructor(const std::string& constructor,
@@ -266,16 +249,15 @@ utils::IdType GlobalInfo::NamespaceVisitor::AddConstructor(const std::string& co
 
   auto constructor_id_iter = global_info_.namespaces_[namespace_stack_.back()].constructors.find(constructor);
 
-  if (constructor_id_iter == global_info_.namespaces_[namespace_stack_.back()].constructors.end()) {
-    size_t id = global_info_.constructors_.size();
-    global_info_.namespaces_[namespace_stack_.back()].constructors[constructor] = id;
-    global_info_.constructors_.push_back(std::move(constructor_info));
-
-    return id;
+  if (constructor_id_iter != global_info_.namespaces_[namespace_stack_.back()].constructors.end()) {
+    error_handling::HandleTypecheckError("More then one constructor with the same name in namespace", base_node);
   }
 
-  error_handling::HandleTypecheckError("More then one constructor with the same name in namespace", base_node);
-  exit(1);
+  utils::IdType id = global_info_.constructors_.size();
+  global_info_.namespaces_[namespace_stack_.back()].constructors[constructor] = id;
+  global_info_.constructors_.push_back(std::move(constructor_info));
+
+  return id;
 }
 
 utils::IdType GlobalInfo::NamespaceVisitor::AddPartition(const std::vector<std::string>& path,
@@ -417,8 +399,8 @@ template<typename T>
 std::optional<T> GlobalInfo::NamespaceVisitor::FindSomething(
     const std::optional<std::vector<std::string>>& path,
     std::function<std::optional<T>(utils::IdType)> search_func) {
-  for (ssize_t i = namespace_stack_.size() - 1; i >= 0; --i) {
-    utils::IdType current_namespace;
+  for (ssize_t i = (ssize_t)namespace_stack_.size() - 1; i >= 0; --i) {
+    utils::IdType current_namespace = 0;
     if (path.has_value()) {
       auto maybe_namespace = FindNamespaceIn(namespace_stack_[i], path.value());
 
@@ -456,4 +438,21 @@ std::optional<utils::IdType> GlobalInfo::NamespaceVisitor::FindNamespaceIn(
   return next_namespace;
 }
 
+std::unordered_map<std::string, utils::IdType>*
+  GlobalInfo::NamespaceVisitor::ChooseNamespaces(std::optional<utils::IsConstModifier> modifier,
+                                                 utils::IdType namespace_id) {
+  std::unordered_map<std::string, utils::IdType>* current_namespaces = nullptr;
+  if (modifier.has_value()) {
+    if (modifier.value() == utils::IsConstModifier::Const) {
+      current_namespaces = &global_info_.namespaces_[namespace_id].const_namespaces;
+    } else {
+      current_namespaces = &global_info_.namespaces_[namespace_id].var_namespaces;
+    }
+  } else {
+    current_namespaces = &global_info_.namespaces_[namespace_id].namespaces;
+  }
+
+  return current_namespaces;
+}
+
 } // namespace info
diff --git a/src/type_check_visitor.cpp b/src/type_check_visitor.cpp
index 32d63b9..40b61b5 100644
--- a/src/type_check_visitor.cpp
+++ b/src/type_check_visitor.cpp
@@ -33,18 +33,22 @@ void TypeCheckVisitor::Visit(NamespaceSources* node) {
 }
 
 void TypeCheckVisitor::Visit(Namespace* node) { // TODO: two var namespces for class: const and var
-  if (node->modifier.has_value()) {
-    if (node->link_typeclass_id_.has_value()) { // TODO: think about typeclass
+  if (node->link_typeclass_id_.has_value()) { // TODO: think about typeclass
 
-      std::vector<utils::IdType> requirements {node->link_typeclass_id_.value()};
-      utils::IdType abstract_type = context_manager_.AddValue(
-        info::type::AbstractType(utils::AbstractTypeModifier::Abstract, node->type, requirements),
-        IsConstModifierToValueType(node->modifier.value()));
+    std::vector<utils::IdType> requirements {node->link_typeclass_id_.value()};
+    utils::IdType abstract_type = context_manager_.AddValue(
+      info::type::AbstractType(utils::AbstractTypeModifier::Abstract, node->type, requirements),
+      IsConstModifierToValueType(node->modifier.value()));
 
+    if (node->modifier.has_value()) {
       context_manager_.EnterVariableContext(utils::ClassInternalVarName,
                                             abstract_type);
-      context_manager_.DefineLocalType(node->type, abstract_type);
-    } else if (node->link_type_id_.has_value()) {
+    } else {
+      context_manager_.EnterContext();
+    }
+    context_manager_.DefineLocalType(node->type, abstract_type);
+  } else if (node->link_type_id_.has_value()) {
+    if (node->modifier.has_value()) {
       auto maybe_type_info = namespace_visitor_.GetGlobalInfo()->GetTypeInfo<info::definition::AnyType>(node->link_type_id_.value());
 
       if (!maybe_type_info.has_value()) {
@@ -61,18 +65,12 @@ void TypeCheckVisitor::Visit(Namespace* node) { // TODO: two var namespces for c
                                   maybe_type_info.value()->modifier,
                                   context_manager_.GetValueManager()),
           IsConstModifierToValueType(node->modifier.value())));
-    }
-  } else {
-    if (node->link_typeclass_id_.has_value()) { // TODO
-      error_handling::HandleTypecheckError("Typeclass can't have not variable namespace", node->base);
+    } else {
+      context_manager_.EnterContext();
     }
 
-    context_manager_.EnterContext();
-  }
-
-  if (node->link_type_id_.has_value()) {
     if (type_namespaces_.count(node->link_type_id_.value()) != 0) {
-        error_handling::HandleTypecheckError("Namespaces of one type one in another", node->base);
+        error_handling::HandleTypecheckError("Namespaces of one type are one in another", node->base);
     }
     type_namespaces_.insert(node->link_type_id_.value());
   }
@@ -413,14 +411,16 @@ void TypeCheckVisitor::Visit(Match* node) { // TODO: move value to match
   }
 
   if (!is_type_found) {
-    type = context_manager_.AddValue(info::type::InternalType::Unit, utils::ValueType::Tmp);
+    error_handling::HandleTypecheckError("Can't find match expression type", node->base);
+    // type = context_manager_.AddValue(info::type::InternalType::Unit, utils::ValueType::Tmp);
   }
 
   current_type_ = type;
 
-  current_type_ = context_manager_.AddValue(
-    info::type::OptionalType(current_type_, context_manager_.GetValueManager()),
-    utils::ValueType::Tmp);
+  // --- instead of optional return value or throw runtime error ---
+  // current_type_ = context_manager_.AddValue(
+  //   info::type::OptionalType(current_type_, context_manager_.GetValueManager()),
+  //   utils::ValueType::Tmp);
 
   context_manager_.ExitContext();
 
diff --git a/tests/test_code.lang b/tests/test_code.lang
index a442cd0..a8392db 100644
--- a/tests/test_code.lang
+++ b/tests/test_code.lang
@@ -39,7 +39,7 @@ typeclass Eq =
   & var ( == ) : Eq -> Bool
   & var ( != ) : Eq -> Bool
 
-namespace const Eq {
+namespace var Eq {
   def ( != ) : x = not: (self == x)
 }
 
@@ -51,13 +51,17 @@ struct Order =
   | GT
 
 typeclass (Ord : #Eq) =
-  & var compare: Ord -> Order
+  & var compare : Ord -> Order
   & var ( < ) : Ord -> Bool
   & var ( >= ) : Ord -> Bool
   & var ( > ) : Ord -> Bool
   & var ( <= ) : Ord -> Bool
-  & var min : Ord -> Ord
-  & var max : Ord -> Ord
+
+decl min ('A : #Ord) : 'A -> 'A -> 'A
+def min : x y = if x < y then x else y
+
+decl max ('A : #Ord) : 'A -> 'A -> 'A
+def max : x y = if x < y then y else x
 
 namespace var Ord {
   def compare : x =
@@ -68,8 +72,6 @@ namespace var Ord {
   def ( >= ) : x = not: (self < x)
   def ( > ) : x = x < self
   def ( <= ) : x = not: (x < self)
-  def min : x = if self < x then self else x
-  def max : x = if self < x then x else self
 }
 
 //