diff --git a/include/.type_info_contexts.hpp.kate-swp b/include/.type_info_contexts.hpp.kate-swp
new file mode 100644
index 0000000..126d73c
Binary files /dev/null and b/include/.type_info_contexts.hpp.kate-swp differ
diff --git a/include/contexts.hpp b/include/contexts.hpp
index 29406e6..f47f6dc 100644
--- a/include/contexts.hpp
+++ b/include/contexts.hpp
@@ -70,6 +70,12 @@ public:
     return contexts_.back().DefineVariable(name, value_id);
   }
 
+  bool DefineLocalType(const std::string& name, utils::IdType type_id) {
+    if (GetLocalType(name).has_value()) {
+      return false;
+    }
+    return contexts_.back().DefineLocalType(name, type_id);
+  }
 
   bool RemoveVariable(const std::string& name) {
     for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
@@ -97,6 +103,16 @@ public:
     return std::nullopt;
   }
 
+  std::optional<utils::IdType> GetLocalType(const std::string& name) {
+    for (ssize_t i = (ssize_t)contexts_.size() - 1; i >= 0; --i) {
+      auto maybe_type = contexts_[i].GetLocalType(name);
+      if (maybe_type.has_value()) {
+        return maybe_type.value();
+      }
+    }
+    return std::nullopt;
+  }
+
 private:
   class Context {
   public:
@@ -114,6 +130,14 @@ private:
       return true;
     }
 
+    bool DefineLocalType(const std::string& name, utils::IdType type_id) {
+      if (local_types_.count(name) > 0) {
+        return false;
+      }
+      local_types_[name] = type_id;
+      return true;
+    }
+
     bool RemoveVariable(const std::string& name) {
       return variables_.erase(name);
     }
@@ -128,8 +152,19 @@ private:
       return variable_iter->second;
     }
 
+    std::optional<utils::IdType> GetLocalType(const std::string& name) {
+      auto local_abstract_type_iter = local_types_.find(name);
+
+      if (local_abstract_type_iter == local_types_.end()) {
+        return std::nullopt;
+      }
+
+      return local_abstract_type_iter->second;
+    }
+
   private:
     std::unordered_map<std::string, utils::IdType> variables_;
+    std::unordered_map<std::string, utils::IdType> local_types_;
   };
 
   std::vector<Context> contexts_;
diff --git a/include/values.hpp b/include/values.hpp
index 07ace42..bd9af09 100644
--- a/include/values.hpp
+++ b/include/values.hpp
@@ -88,9 +88,9 @@ public:
 struct ArrayValue {
 public:
   ArrayValue() = default;
-  explicit ArrayValue(const std::vector<utils::IdType>& elements,
+  explicit ArrayValue(std::vector<utils::IdType>&& elements,
                       bool is_constant_size)
-    : elements(elements), is_constant_size(is_constant_size) {}
+    : elements(std::move(elements)), is_constant_size(is_constant_size) {}
 
 public:
   std::vector<utils::IdType> elements;
diff --git a/src/execute_visitor.cpp b/src/execute_visitor.cpp
index 14e3cee..985d92e 100644
--- a/src/execute_visitor.cpp
+++ b/src/execute_visitor.cpp
@@ -34,14 +34,14 @@ void ExecuteVisitor::Visit(Namespace* node) { // never used ??
 void ExecuteVisitor::Visit(ImportStatement* node) {} // no value
 void ExecuteVisitor::Visit(AliasDefinitionStatement* node) {} // no value
 
-void ExecuteVisitor::Visit(VariableDefinitionStatement* node) {
+void ExecuteVisitor::Visit(VariableDefinitionStatement* node) { // visited on function call
   Visitor::Visit(node->name);
   Visitor::Visit(node->value);
 }
 
 void ExecuteVisitor::Visit(FunctionDeclaration* node) {} // no value
 
-void ExecuteVisitor::Visit(FunctionDefinitionStatement* node) {
+void ExecuteVisitor::Visit(FunctionDefinitionStatement* node) { // visited on function call
   // Visit(node->definition.get());
   Visitor::Visit(node->value);
 }
@@ -64,7 +64,9 @@ void ExecuteVisitor::Visit(TypeConstructorPatternParameter* node) {
   Visitor::Visit(node->value);
 }
 
+// TODO
 void ExecuteVisitor::Visit(TypeConstructorPattern* node) {
+  // TODO: not only tuples
   Visit(node->constructor.get());
   for (auto& parameter : node->parameters) {
     Visit(&parameter);
@@ -90,11 +92,23 @@ void ExecuteVisitor::Visit(Match* node) {
 
 void ExecuteVisitor::Visit(Condition* node) {
   for (size_t i = 0; i < node->conditions.size(); ++i) {
-      Visitor::Visit(node->conditions[i]);
+    if (HandleCondition(node->conditions[i], node->base)) {
       Visitor::Visit(node->statements[i]);
+
+      if (node->statements.size() == node->conditions.size()) {
+        current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
+          info::value::OptionalValue(current_value_),
+          utils::ValueType::Tmp); // take value type from current_value_ ??
+      }
+      return; // current_value_ passed from statement
+    }
   }
   if (node->statements.size() > node->conditions.size()) {
     Visitor::Visit(node->statements[node->conditions.size()]);
+  } else {
+    current_value_ = context_manager_.AddValue<info::value::OptionalValue>(
+      info::value::OptionalValue(),
+      utils::ValueType::Tmp);
   }
 }
 
@@ -115,7 +129,7 @@ void ExecuteVisitor::Visit(DoWhileLoop* node) {
   } while(HandleCondition(node->condition, node->base));
 
   current_value_ = context_manager_.AddValue<info::value::ArrayValue>(
-    info::value::ArrayValue(result, false),
+    info::value::ArrayValue(std::move(result), false),
     utils::ValueType::Tmp);
 }
 
@@ -136,7 +150,7 @@ void ExecuteVisitor::Visit(WhileLoop* node) {
   }
 
   current_value_ = context_manager_.AddValue<info::value::ArrayValue>(
-    info::value::ArrayValue(result, false),
+    info::value::ArrayValue(std::move(result), false),
     utils::ValueType::Tmp);
 }
 void ExecuteVisitor::Visit(ForLoop* node) {
@@ -164,7 +178,7 @@ void ExecuteVisitor::Visit(ForLoop* node) {
   }
 
   current_value_ = context_manager_.AddValue<info::value::ArrayValue>(
-    info::value::ArrayValue(result, false),
+    info::value::ArrayValue(std::move(result), false),
     utils::ValueType::Tmp);
 }
 
@@ -185,13 +199,16 @@ void ExecuteVisitor::Visit(LoopLoop* node) {
   }
 
   current_value_ = context_manager_.AddValue<info::value::ArrayValue>(
-    info::value::ArrayValue(result, false),
+    info::value::ArrayValue(std::move(result), false),
     utils::ValueType::Tmp);
 }
 
 // Statements, expressions, blocks, etc. -----------------
 
 void ExecuteVisitor::Visit(Block* node) {
+  // type_info_context_manager_.EnterContext(); // not needed ??
+  context_manager_.EnterContext();
+
   for (auto& statement : node->statements) {
     return_value_ = std::nullopt;
     Visitor::Visit(statement);
@@ -200,6 +217,9 @@ void ExecuteVisitor::Visit(Block* node) {
       return;
     }
   }
+  // context_manager_.ExitContext();
+  // type_info_context_manager_.ExitContext(); // not needed ??
+
   current_value_ = context_manager_.AddValue<info::value::InternalValue>(
     info::value::InternalValue(info::value::Unit()),
     utils::ValueType::Tmp);
@@ -288,8 +308,9 @@ void ExecuteVisitor::Visit(TupleExpression* node) {
     fields.push_back({std::nullopt, current_value_});
   }
 
-  current_value_ = context_manager_.AddValue<info::value::TupleValue>(info::value::TupleValue(std::move(fields)),
-                                                     utils::ValueType::Tmp);
+  current_value_ = context_manager_.AddValue<info::value::TupleValue>(
+    info::value::TupleValue(std::move(fields)),
+    utils::ValueType::Tmp);
 }
 
 // TODO
@@ -316,7 +337,9 @@ void ExecuteVisitor::Visit(TypeConstructorParameter* node) {
   Visitor::Visit(node->value);
 }
 
+// TODO
 void ExecuteVisitor::Visit(TypeConstructor* node) {
+  // TODO: not only tuples
   Visit(node->constructor.get());
   for (auto& parameter : node->parameters) {
     Visit(&parameter);
@@ -330,9 +353,17 @@ void ExecuteVisitor::Visit(LambdaFunction* node) {
 }
 
 void ExecuteVisitor::Visit(ArrayExpression* node) {
+  std::vector<utils::IdType> elements;
+
+  elements.reserve(node->elements.size());
   for (auto& element : node->elements) {
     Visitor::Visit(element);
+    elements.push_back(current_value_);
   }
+
+  current_value_ = context_manager_.AddValue<info::value::ArrayValue>(
+    info::value::ArrayValue(std::move(elements), true), // maybe size not fixed??
+    utils::ValueType::Tmp);
 }
 
 // Name
diff --git a/src/type_check_visitor.cpp b/src/type_check_visitor.cpp
index 7f7bbd2..6d1ae12 100644
--- a/src/type_check_visitor.cpp
+++ b/src/type_check_visitor.cpp
@@ -736,7 +736,7 @@ void TypeCheckVisitor::Visit(AccessExpression* node) {
 
 // Other Expressions
 
-// TODO
+// TODO: better structure, ...
 // TODO: builtin functions/methods
 // TODO: alias types, abstract types, etc.
 // TODO: deduce function parameter types