diff --git a/libsolidity/AST.cpp b/libsolidity/AST.cpp
index 8555d8c6d..15da9e0d8 100644
--- a/libsolidity/AST.cpp
+++ b/libsolidity/AST.cpp
@@ -250,46 +250,42 @@ void Literal::accept(ASTVisitor& _visitor)
 
 void Statement::expectType(Expression& _expression, const Type& _expectedType)
 {
-	if (!_expression.checkTypeRequirements()->isImplicitlyConvertibleTo(_expectedType))
+	_expression.checkTypeRequirements();
+	if (!_expression.getType()->isImplicitlyConvertibleTo(_expectedType))
 		BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Type not implicitly convertible "
 															 "to expected type."));
 	//@todo provide more information to the exception
 }
 
-ptr<Type> Block::checkTypeRequirements()
+void Block::checkTypeRequirements()
 {
-	for (ptr<Statement> const& statement: m_statements)
+	for (std::shared_ptr<Statement> const& statement: m_statements)
 		statement->checkTypeRequirements();
-	return ptr<Type>();
 }
 
-ptr<Type> IfStatement::checkTypeRequirements()
+void IfStatement::checkTypeRequirements()
 {
 	expectType(*m_condition, BoolType());
 	m_trueBody->checkTypeRequirements();
 	if (m_falseBody)
 		m_falseBody->checkTypeRequirements();
-	return ptr<Type>();
 }
 
-ptr<Type> WhileStatement::checkTypeRequirements()
+void WhileStatement::checkTypeRequirements()
 {
 	expectType(*m_condition, BoolType());
 	m_body->checkTypeRequirements();
-	return ptr<Type>();
 }
 
-ptr<Type> Continue::checkTypeRequirements()
+void Continue::checkTypeRequirements()
 {
-	return ptr<Type>();
 }
 
-ptr<Type> Break::checkTypeRequirements()
+void Break::checkTypeRequirements()
 {
-	return ptr<Type>();
 }
 
-ptr<Type> Return::checkTypeRequirements()
+void Return::checkTypeRequirements()
 {
 	BOOST_ASSERT(m_returnParameters != nullptr);
 	if (m_returnParameters->getParameters().size() != 1)
@@ -299,10 +295,9 @@ ptr<Type> Return::checkTypeRequirements()
 	// this could later be changed such that the paramaters type is an anonymous struct type,
 	// but for now, we only allow one return parameter
 	expectType(*m_expression, *m_returnParameters->getParameters().front()->getType());
-	return ptr<Type>();
 }
 
-ptr<Type> VariableDefinition::checkTypeRequirements()
+void VariableDefinition::checkTypeRequirements()
 {
 	// Variables can be declared without type (with "var"), in which case the first assignment
 	// setsthe type.
@@ -313,17 +308,20 @@ ptr<Type> VariableDefinition::checkTypeRequirements()
 		if (m_variable->getType())
 			expectType(*m_value, *m_variable->getType());
 		else
+		{
 			// no type declared and no previous assignment, infer the type
-			m_variable->setType(m_value->checkTypeRequirements());
+			m_value->checkTypeRequirements();
+			m_variable->setType(m_value->getType());
+		}
 	}
-	return ptr<Type>();
 }
 
-ptr<Type> Assignment::checkTypeRequirements()
+void Assignment::checkTypeRequirements()
 {
 	//@todo lefthandside actually has to be assignable
 	// add a feature to the type system to check that
-	expectType(*m_rightHandSide, *m_leftHandSide->checkTypeRequirements());
+	m_leftHandSide->checkTypeRequirements();
+	expectType(*m_rightHandSide, *m_leftHandSide->getType());
 	m_type = m_leftHandSide->getType();
 	if (m_assigmentOperator != Token::ASSIGN)
 	{
@@ -331,19 +329,18 @@ ptr<Type> Assignment::checkTypeRequirements()
 		if (!m_type->acceptsBinaryOperator(Token::AssignmentToBinaryOp(m_assigmentOperator)))
 			BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Operator not compatible with type."));
 	}
-	return m_type;
 }
 
-ptr<Type> UnaryOperation::checkTypeRequirements()
+void UnaryOperation::checkTypeRequirements()
 {
 	// INC, DEC, NOT, BIT_NOT, DELETE
-	m_type = m_subExpression->checkTypeRequirements();
+	m_subExpression->checkTypeRequirements();
+	m_type = m_subExpression->getType();
 	if (m_type->acceptsUnaryOperator(m_operator))
 		BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Unary operator not compatible with type."));
-	return m_type;
 }
 
-ptr<Type> BinaryOperation::checkTypeRequirements()
+void BinaryOperation::checkTypeRequirements()
 {
 	m_right->checkTypeRequirements();
 	m_left->checkTypeRequirements();
@@ -362,19 +359,18 @@ ptr<Type> BinaryOperation::checkTypeRequirements()
 		if (!m_commonType->acceptsBinaryOperator(m_operator))
 			BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Operator not compatible with type."));
 	}
-	return m_type;
 }
 
-ptr<Type> FunctionCall::checkTypeRequirements()
+void FunctionCall::checkTypeRequirements()
 {
 	m_expression->checkTypeRequirements();
-	for (ptr<Expression> const& argument: m_arguments)
+	for (ASTPointer<Expression> const& argument: m_arguments)
 		argument->checkTypeRequirements();
-	ptr<Type> expressionType = m_expression->getType();
-	Type::Category const category = expressionType->getCategory();
+	Type const& expressionType = *m_expression->getType();
+	Type::Category const category = expressionType.getCategory();
 	if (category == Type::Category::TYPE)
 	{
-		TypeType* type = dynamic_cast<TypeType*>(expressionType.get());
+		TypeType const* type = dynamic_cast<TypeType const*>(&expressionType);
 		BOOST_ASSERT(type != nullptr);
 		//@todo for structs, we have to check the number of arguments to be equal to the
 		// number of non-mapping members
@@ -391,10 +387,10 @@ ptr<Type> FunctionCall::checkTypeRequirements()
 		//@todo would be nice to create a struct type from the arguments
 		// and then ask if that is implicitly convertible to the struct represented by the
 		// function parameters
-		FunctionType* function = dynamic_cast<FunctionType*>(expressionType.get());
+		FunctionType const* function = dynamic_cast<FunctionType const*>(&expressionType);
 		BOOST_ASSERT(function != nullptr);
 		FunctionDefinition const& fun = function->getFunction();
-		std::vector<ptr<VariableDeclaration>> const& parameters = fun.getParameters();
+		std::vector<ASTPointer<VariableDeclaration>> const& parameters = fun.getParameters();
 		if (parameters.size() != m_arguments.size())
 			BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Wrong argument count for "
 								  "function call."));
@@ -413,24 +409,21 @@ ptr<Type> FunctionCall::checkTypeRequirements()
 	{
 		BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Type does not support invocation."));
 	}
-	return m_type;
 }
 
-ptr<Type> MemberAccess::checkTypeRequirements()
+void MemberAccess::checkTypeRequirements()
 {
 	BOOST_ASSERT(false); // not yet implemented
 	// m_type = ;
-	return m_type;
 }
 
-ptr<Type> IndexAccess::checkTypeRequirements()
+void IndexAccess::checkTypeRequirements()
 {
 	BOOST_ASSERT(false); // not yet implemented
 	// m_type = ;
-	return m_type;
 }
 
-ptr<Type> Identifier::checkTypeRequirements()
+void Identifier::checkTypeRequirements()
 {
 	BOOST_ASSERT(m_referencedDeclaration != nullptr);
 	//@todo these dynamic casts here are not really nice...
@@ -444,11 +437,11 @@ ptr<Type> Identifier::checkTypeRequirements()
 	VariableDeclaration* variable = dynamic_cast<VariableDeclaration*>(m_referencedDeclaration);
 	if (variable != nullptr)
 	{
-		if (variable->getType().get() == nullptr)
+		if (!variable->getType())
 			BOOST_THROW_EXCEPTION(TypeError() << errinfo_comment("Variable referenced before type "
 																 "could be determined."));
 		m_type = variable->getType();
-		return m_type;
+		return;
 	}
 	//@todo can we unify these with TypeName::toType()?
 	StructDefinition* structDef = dynamic_cast<StructDefinition*>(m_referencedDeclaration);
@@ -456,7 +449,7 @@ ptr<Type> Identifier::checkTypeRequirements()
 	{
 		// note that we do not have a struct type here
 		m_type = std::make_shared<TypeType>(std::make_shared<StructType>(*structDef));
-		return m_type;
+		return;
 	}
 	FunctionDefinition* functionDef = dynamic_cast<FunctionDefinition*>(m_referencedDeclaration);
 	if (functionDef != nullptr)
@@ -465,28 +458,25 @@ ptr<Type> Identifier::checkTypeRequirements()
 		// Calling a function (e.g. function(12), otherContract.function(34)) does not do a type
 		// conversion.
 		m_type = std::make_shared<FunctionType>(*functionDef);
-		return m_type;
+		return;
 	}
 	ContractDefinition* contractDef = dynamic_cast<ContractDefinition*>(m_referencedDeclaration);
 	if (contractDef != nullptr)
 	{
 		m_type = std::make_shared<TypeType>(std::make_shared<ContractType>(*contractDef));
-		return m_type;
+		return;
 	}
 	BOOST_ASSERT(false); // declaration reference of unknown/forbidden type
-	return m_type;
 }
 
-ptr<Type> ElementaryTypeNameExpression::checkTypeRequirements()
+void ElementaryTypeNameExpression::checkTypeRequirements()
 {
 	m_type = std::make_shared<TypeType>(Type::fromElementaryTypeName(m_typeToken));
-	return m_type;
 }
 
-ptr<Type> Literal::checkTypeRequirements()
+void Literal::checkTypeRequirements()
 {
 	m_type = Type::forLiteral(*this);
-	return m_type;
 }
 
 }
diff --git a/libsolidity/AST.h b/libsolidity/AST.h
index 661e10a7e..319fc0581 100644
--- a/libsolidity/AST.h
+++ b/libsolidity/AST.h
@@ -51,9 +51,9 @@ public:
 
 	virtual void accept(ASTVisitor& _visitor) = 0;
 	template <class T>
-	static void listAccept(std::vector<ptr<T>>& _list, ASTVisitor& _visitor)
+	static void listAccept(std::vector<ASTPointer<T>>& _list, ASTVisitor& _visitor)
 	{
-		for (ptr<T>& element: _list)
+		for (ASTPointer<T>& element: _list)
 			element->accept(_visitor);
 	}
 
@@ -65,22 +65,22 @@ private:
 class Declaration: public ASTNode
 {
 public:
-	Declaration(Location const& _location, ptr<ASTString> const& _name)
+	Declaration(Location const& _location, ASTPointer<ASTString> const& _name)
 		: ASTNode(_location), m_name(_name) {}
 
 	const ASTString& getName() const { return *m_name; }
 private:
-	ptr<ASTString> m_name;
+	ASTPointer<ASTString> m_name;
 };
 
 class ContractDefinition: public Declaration
 {
 public:
 	ContractDefinition(Location const& _location,
-					   ptr<ASTString> const& _name,
-					   std::vector<ptr<StructDefinition>> const& _definedStructs,
-					   std::vector<ptr<VariableDeclaration>> const& _stateVariables,
-					   std::vector<ptr<FunctionDefinition>> const& _definedFunctions)
+					   ASTPointer<ASTString> const& _name,
+					   std::vector<ASTPointer<StructDefinition>> const& _definedStructs,
+					   std::vector<ASTPointer<VariableDeclaration>> const& _stateVariables,
+					   std::vector<ASTPointer<FunctionDefinition>> const& _definedFunctions)
 		: Declaration(_location, _name),
 		  m_definedStructs(_definedStructs),
 		  m_stateVariables(_stateVariables),
@@ -89,26 +89,26 @@ public:
 
 	virtual void accept(ASTVisitor& _visitor) override;
 
-	std::vector<ptr<StructDefinition>> const& getDefinedStructs() { return m_definedStructs; }
-	std::vector<ptr<VariableDeclaration>> const& getStateVariables() { return m_stateVariables; }
-	std::vector<ptr<FunctionDefinition>> const& getDefinedFunctions() { return m_definedFunctions; }
+	std::vector<ASTPointer<StructDefinition>> const& getDefinedStructs() { return m_definedStructs; }
+	std::vector<ASTPointer<VariableDeclaration>> const& getStateVariables() { return m_stateVariables; }
+	std::vector<ASTPointer<FunctionDefinition>> const& getDefinedFunctions() { return m_definedFunctions; }
 private:
-	std::vector<ptr<StructDefinition>> m_definedStructs;
-	std::vector<ptr<VariableDeclaration>> m_stateVariables;
-	std::vector<ptr<FunctionDefinition>> m_definedFunctions;
+	std::vector<ASTPointer<StructDefinition>> m_definedStructs;
+	std::vector<ASTPointer<VariableDeclaration>> m_stateVariables;
+	std::vector<ASTPointer<FunctionDefinition>> m_definedFunctions;
 };
 
 class StructDefinition: public Declaration
 {
 public:
 	StructDefinition(Location const& _location,
-					 ptr<ASTString> const& _name,
-					 std::vector<ptr<VariableDeclaration>> const& _members)
+					 ASTPointer<ASTString> const& _name,
+					 std::vector<ASTPointer<VariableDeclaration>> const& _members)
 		: Declaration(_location, _name), m_members(_members) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 
 private:
-	std::vector<ptr<VariableDeclaration>> m_members;
+	std::vector<ASTPointer<VariableDeclaration>> m_members;
 };
 
 /// Used as function parameter list and return list
@@ -117,23 +117,23 @@ private:
 class ParameterList: public ASTNode
 {
 public:
-	ParameterList(Location const& _location, std::vector<ptr<VariableDeclaration>> const& _parameters)
+	ParameterList(Location const& _location, std::vector<ASTPointer<VariableDeclaration>> const& _parameters)
 		: ASTNode(_location), m_parameters(_parameters) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 
-	std::vector<ptr<VariableDeclaration>> const& getParameters() { return m_parameters; }
+	std::vector<ASTPointer<VariableDeclaration>> const& getParameters() { return m_parameters; }
 private:
-	std::vector<ptr<VariableDeclaration>> m_parameters;
+	std::vector<ASTPointer<VariableDeclaration>> m_parameters;
 };
 
 class FunctionDefinition: public Declaration
 {
 public:
-	FunctionDefinition(Location const& _location, ptr<ASTString> const& _name, bool _isPublic,
-					   ptr<ParameterList> const& _parameters,
+	FunctionDefinition(Location const& _location, ASTPointer<ASTString> const& _name, bool _isPublic,
+					   ASTPointer<ParameterList> const& _parameters,
 					   bool _isDeclaredConst,
-					   ptr<ParameterList> const& _returnParameters,
-					   ptr<Block> const& _body)
+					   ASTPointer<ParameterList> const& _returnParameters,
+					   ASTPointer<Block> const& _body)
 		: Declaration(_location, _name), m_isPublic(_isPublic), m_parameters(_parameters),
 		  m_isDeclaredConst(_isDeclaredConst), m_returnParameters(_returnParameters),
 		  m_body(_body) {}
@@ -141,23 +141,23 @@ public:
 
 	bool isPublic() const { return m_isPublic; }
 	bool isDeclaredConst() const { return m_isDeclaredConst; }
-	std::vector<ptr<VariableDeclaration>> const& getParameters() const { return m_parameters->getParameters(); }
+	std::vector<ASTPointer<VariableDeclaration>> const& getParameters() const { return m_parameters->getParameters(); }
 	ParameterList& getParameterList() { return *m_parameters; }
-	ptr<ParameterList> const& getReturnParameterList() const { return m_returnParameters; }
+	ASTPointer<ParameterList> const& getReturnParameterList() const { return m_returnParameters; }
 	Block& getBody() { return *m_body; }
 private:
 	bool m_isPublic;
-	ptr<ParameterList> m_parameters;
+	ASTPointer<ParameterList> m_parameters;
 	bool m_isDeclaredConst;
-	ptr<ParameterList> m_returnParameters;
-	ptr<Block> m_body;
+	ASTPointer<ParameterList> m_returnParameters;
+	ASTPointer<Block> m_body;
 };
 
 class VariableDeclaration: public Declaration
 {
 public:
-	VariableDeclaration(Location const& _location, ptr<TypeName> const& _type,
-						ptr<ASTString> const& _name)
+	VariableDeclaration(Location const& _location, ASTPointer<TypeName> const& _type,
+						ASTPointer<ASTString> const& _name)
 		: Declaration(_location, _name), m_typeName(_type) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 
@@ -166,12 +166,12 @@ public:
 
 	//! Returns the declared or inferred type. Can be an empty pointer if no type was explicitly
 	//! declared and there is no assignment to the variable that fixes the type.
-	ptr<Type> const& getType() const { return m_type; }
-	void setType(ptr<Type> const& _type) { m_type = _type; }
+	std::shared_ptr<Type const> const& getType() const { return m_type; }
+	void setType(std::shared_ptr<Type const> const& _type) { m_type = _type; }
 private:
-	ptr<TypeName> m_typeName; ///< can be empty ("var")
+	ASTPointer<TypeName> m_typeName; ///< can be empty ("var")
 
-	ptr<Type> m_type;
+	std::shared_ptr<Type const> m_type;
 };
 
 /// types
@@ -183,7 +183,7 @@ public:
 	explicit TypeName(Location const& _location): ASTNode(_location) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 
-	virtual ptr<Type> toType() = 0;
+	virtual std::shared_ptr<Type> toType() = 0;
 };
 
 /// any pre-defined type that is not a mapping
@@ -193,7 +193,7 @@ public:
 	explicit ElementaryTypeName(Location const& _location, Token::Value _type)
 		: TypeName(_location), m_type(_type) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> toType() override { return Type::fromElementaryTypeName(m_type); }
+	virtual std::shared_ptr<Type> toType() override { return Type::fromElementaryTypeName(m_type); }
 
 	Token::Value getType() const { return m_type; }
 private:
@@ -203,16 +203,16 @@ private:
 class UserDefinedTypeName: public TypeName
 {
 public:
-	UserDefinedTypeName(Location const& _location, ptr<ASTString> const& _name)
+	UserDefinedTypeName(Location const& _location, ASTPointer<ASTString> const& _name)
 		: TypeName(_location), m_name(_name) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> toType() override { return Type::fromUserDefinedTypeName(*this); }
+	virtual std::shared_ptr<Type> toType() override { return Type::fromUserDefinedTypeName(*this); }
 
 	const ASTString& getName() const { return *m_name; }
 	void setReferencedStruct(StructDefinition& _referencedStruct) { m_referencedStruct = &_referencedStruct; }
 	StructDefinition const* getReferencedStruct() const { return m_referencedStruct; }
 private:
-	ptr<ASTString> m_name;
+	ASTPointer<ASTString> m_name;
 
 	StructDefinition* m_referencedStruct;
 };
@@ -220,14 +220,14 @@ private:
 class Mapping: public TypeName
 {
 public:
-	Mapping(Location const& _location, ptr<ElementaryTypeName> const& _keyType,
-			ptr<TypeName> const& _valueType)
+	Mapping(Location const& _location, ASTPointer<ElementaryTypeName> const& _keyType,
+			ASTPointer<TypeName> const& _valueType)
 		: TypeName(_location), m_keyType(_keyType), m_valueType(_valueType) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> toType() override { return Type::fromMapping(*this); }
+	virtual std::shared_ptr<Type> toType() override { return Type::fromMapping(*this); }
 private:
-	ptr<ElementaryTypeName> m_keyType;
-	ptr<TypeName> m_valueType;
+	ASTPointer<ElementaryTypeName> m_keyType;
+	ASTPointer<TypeName> m_valueType;
 };
 
 /// @}
@@ -244,7 +244,7 @@ public:
 	//! Check all type requirements, throws exception if some requirement is not met.
 	//! For expressions, this also returns the inferred type of the expression. For other
 	//! statements, returns the empty pointer.
-	virtual ptr<Type> checkTypeRequirements() = 0;
+	virtual void checkTypeRequirements() = 0;
 protected:
 	//! Check that the inferred type for _expression is _expectedType or at least implicitly
 	//! convertible to _expectedType. If not, throw exception.
@@ -254,28 +254,28 @@ protected:
 class Block: public Statement
 {
 public:
-	Block(Location const& _location, std::vector<ptr<Statement>> const& _statements)
+	Block(Location const& _location, std::vector<ASTPointer<Statement>> const& _statements)
 		: Statement(_location), m_statements(_statements) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	std::vector<ptr<Statement>> m_statements;
+	std::vector<ASTPointer<Statement>> m_statements;
 };
 
 class IfStatement: public Statement
 {
 public:
-	IfStatement(Location const& _location, ptr<Expression> const& _condition,
-				ptr<Statement> const& _trueBody, ptr<Statement> const& _falseBody)
+	IfStatement(Location const& _location, ASTPointer<Expression> const& _condition,
+				ASTPointer<Statement> const& _trueBody, ASTPointer<Statement> const& _falseBody)
 		: Statement(_location), m_condition(_condition),
 		  m_trueBody(_trueBody), m_falseBody(_falseBody) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	ptr<Expression> m_condition;
-	ptr<Statement> m_trueBody;
-	ptr<Statement> m_falseBody; //< "else" part, optional
+	ASTPointer<Expression> m_condition;
+	ASTPointer<Statement> m_trueBody;
+	ASTPointer<Statement> m_falseBody; //< "else" part, optional
 };
 
 class BreakableStatement: public Statement
@@ -288,14 +288,14 @@ public:
 class WhileStatement: public BreakableStatement
 {
 public:
-	WhileStatement(Location const& _location, ptr<Expression> const& _condition,
-				   ptr<Statement> const& _body)
+	WhileStatement(Location const& _location, ASTPointer<Expression> const& _condition,
+				   ASTPointer<Statement> const& _body)
 		: BreakableStatement(_location), m_condition(_condition), m_body(_body) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	ptr<Expression> m_condition;
-	ptr<Statement> m_body;
+	ASTPointer<Expression> m_condition;
+	ASTPointer<Statement> m_body;
 };
 
 class Continue: public Statement
@@ -303,7 +303,7 @@ class Continue: public Statement
 public:
 	Continue(Location const& _location): Statement(_location) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 };
 
 class Break: public Statement
@@ -311,20 +311,20 @@ class Break: public Statement
 public:
 	Break(Location const& _location): Statement(_location) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 };
 
 class Return: public Statement
 {
 public:
-	Return(Location const& _location, ptr<Expression> _expression)
+	Return(Location const& _location, ASTPointer<Expression> _expression)
 		: Statement(_location), m_expression(_expression) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	void setFunctionReturnParameters(ParameterList& _parameters) { m_returnParameters = &_parameters; }
 private:
-	ptr<Expression> m_expression; //< value to return, optional
+	ASTPointer<Expression> m_expression; //< value to return, optional
 
 	ParameterList* m_returnParameters; //< extracted from the function declaration
 };
@@ -332,24 +332,25 @@ private:
 class VariableDefinition: public Statement
 {
 public:
-	VariableDefinition(Location const& _location, ptr<VariableDeclaration> _variable,
-					   ptr<Expression> _value)
+	VariableDefinition(Location const& _location, ASTPointer<VariableDeclaration> _variable,
+					   ASTPointer<Expression> _value)
 		: Statement(_location), m_variable(_variable), m_value(_value) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 private:
-	ptr<VariableDeclaration> m_variable;
-	ptr<Expression> m_value; ///< can be missing
+	ASTPointer<VariableDeclaration> m_variable;
+	ASTPointer<Expression> m_value; ///< can be missing
 };
 
 class Expression: public Statement
 {
 public:
 	Expression(Location const& _location): Statement(_location) {}
-	ptr<Type> const& getType() { return m_type; }
+	std::shared_ptr<Type const> const& getType() const { return m_type; }
 protected:
-	ptr<Type> m_type;
+	//! Inferred type of the expression, only filled after a call to checkTypeRequirements().
+	std::shared_ptr<Type const> m_type;
 };
 
 /// @}
@@ -360,95 +361,95 @@ protected:
 class Assignment: public Expression
 {
 public:
-	Assignment(Location const& _location, ptr<Expression> const& _leftHandSide,
-			   Token::Value _assignmentOperator, ptr<Expression> const& _rightHandSide)
+	Assignment(Location const& _location, ASTPointer<Expression> const& _leftHandSide,
+			   Token::Value _assignmentOperator, ASTPointer<Expression> const& _rightHandSide)
 		: Expression(_location), m_leftHandSide(_leftHandSide),
 		  m_assigmentOperator(_assignmentOperator), m_rightHandSide(_rightHandSide) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	Token::Value getAssignmentOperator() const { return m_assigmentOperator; }
 private:
-	ptr<Expression> m_leftHandSide;
+	ASTPointer<Expression> m_leftHandSide;
 	Token::Value m_assigmentOperator;
-	ptr<Expression> m_rightHandSide;
+	ASTPointer<Expression> m_rightHandSide;
 };
 
 class UnaryOperation: public Expression
 {
 public:
 	UnaryOperation(Location const& _location, Token::Value _operator,
-				   ptr<Expression> const& _subExpression, bool _isPrefix)
+				   ASTPointer<Expression> const& _subExpression, bool _isPrefix)
 		: Expression(_location), m_operator(_operator),
 		  m_subExpression(_subExpression), m_isPrefix(_isPrefix) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	Token::Value getOperator() const { return m_operator; }
 	bool isPrefixOperation() const { return m_isPrefix; }
 private:
 	Token::Value m_operator;
-	ptr<Expression> m_subExpression;
+	ASTPointer<Expression> m_subExpression;
 	bool m_isPrefix;
 };
 
 class BinaryOperation: public Expression
 {
 public:
-	BinaryOperation(Location const& _location, ptr<Expression> const& _left,
-					Token::Value _operator, ptr<Expression> const& _right)
+	BinaryOperation(Location const& _location, ASTPointer<Expression> const& _left,
+					Token::Value _operator, ASTPointer<Expression> const& _right)
 		: Expression(_location), m_left(_left), m_operator(_operator), m_right(_right) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	Token::Value getOperator() const { return m_operator; }
 private:
-	ptr<Expression> m_left;
+	ASTPointer<Expression> m_left;
 	Token::Value m_operator;
-	ptr<Expression> m_right;
+	ASTPointer<Expression> m_right;
 
-	ptr<Type> m_commonType;
+	std::shared_ptr<Type const> m_commonType;
 };
 
 /// Can be ordinary function call, type cast or struct construction.
 class FunctionCall: public Expression
 {
 public:
-	FunctionCall(Location const& _location, ptr<Expression> const& _expression,
-				 std::vector<ptr<Expression>> const& _arguments)
+	FunctionCall(Location const& _location, ASTPointer<Expression> const& _expression,
+				 std::vector<ASTPointer<Expression>> const& _arguments)
 		: Expression(_location), m_expression(_expression), m_arguments(_arguments) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	ptr<Expression> m_expression;
-	std::vector<ptr<Expression>> m_arguments;
+	ASTPointer<Expression> m_expression;
+	std::vector<ASTPointer<Expression>> m_arguments;
 };
 
 class MemberAccess: public Expression
 {
 public:
-	MemberAccess(Location const& _location, ptr<Expression> _expression,
-				 ptr<ASTString> const& _memberName)
+	MemberAccess(Location const& _location, ASTPointer<Expression> _expression,
+				 ASTPointer<ASTString> const& _memberName)
 		: Expression(_location), m_expression(_expression), m_memberName(_memberName) {}
 	virtual void accept(ASTVisitor& _visitor) override;
 	const ASTString& getMemberName() const { return *m_memberName; }
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	ptr<Expression> m_expression;
-	ptr<ASTString> m_memberName;
+	ASTPointer<Expression> m_expression;
+	ASTPointer<ASTString> m_memberName;
 };
 
 class IndexAccess: public Expression
 {
 public:
-	IndexAccess(Location const& _location, ptr<Expression> const& _base,
-				ptr<Expression> const& _index)
+	IndexAccess(Location const& _location, ASTPointer<Expression> const& _base,
+				ASTPointer<Expression> const& _index)
 		: Expression(_location), m_base(_base), m_index(_index) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 private:
-	ptr<Expression> m_base;
-	ptr<Expression> m_index;
+	ASTPointer<Expression> m_base;
+	ASTPointer<Expression> m_index;
 };
 
 class PrimaryExpression: public Expression
@@ -460,16 +461,16 @@ public:
 class Identifier: public PrimaryExpression
 {
 public:
-	Identifier(Location const& _location, ptr<ASTString> const& _name)
+	Identifier(Location const& _location, ASTPointer<ASTString> const& _name)
 		: PrimaryExpression(_location), m_name(_name) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	ASTString const& getName() const { return *m_name; }
 	void setReferencedDeclaration(Declaration& _referencedDeclaration) { m_referencedDeclaration = &_referencedDeclaration; }
 	Declaration* getReferencedDeclaration() { return m_referencedDeclaration; }
 private:
-	ptr<ASTString> m_name;
+	ASTPointer<ASTString> m_name;
 
 	//! Declaration the name refers to.
 	Declaration* m_referencedDeclaration;
@@ -481,7 +482,7 @@ public:
 	ElementaryTypeNameExpression(Location const& _location, Token::Value _typeToken)
 		: PrimaryExpression(_location), m_typeToken(_typeToken) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	Token::Value getTypeToken() const { return m_typeToken; }
 private:
@@ -491,16 +492,16 @@ private:
 class Literal: public PrimaryExpression
 {
 public:
-	Literal(Location const& _location, Token::Value _token, ptr<ASTString> const& _value)
+	Literal(Location const& _location, Token::Value _token, ASTPointer<ASTString> const& _value)
 		: PrimaryExpression(_location), m_token(_token), m_value(_value) {}
 	virtual void accept(ASTVisitor& _visitor) override;
-	virtual ptr<Type> checkTypeRequirements() override;
+	virtual void checkTypeRequirements() override;
 
 	Token::Value getToken() const { return m_token; }
 	ASTString const& getValue() const { return *m_value; }
 private:
 	Token::Value m_token;
-	ptr<ASTString> m_value;
+	ASTPointer<ASTString> m_value;
 };
 
 /// @}
diff --git a/libsolidity/ASTForward.h b/libsolidity/ASTForward.h
index 46fe8393a..c9a780f5f 100644
--- a/libsolidity/ASTForward.h
+++ b/libsolidity/ASTForward.h
@@ -69,7 +69,7 @@ class Literal;
 // not do reference counting but point to a special memory area that is completely released
 // explicitly.
 template <class T>
-using ptr = std::shared_ptr<T>;
+using ASTPointer = std::shared_ptr<T>;
 
 using ASTString = std::string;
 
diff --git a/libsolidity/ASTPrinter.cpp b/libsolidity/ASTPrinter.cpp
index 1ff0c52e7..af8f20157 100644
--- a/libsolidity/ASTPrinter.cpp
+++ b/libsolidity/ASTPrinter.cpp
@@ -28,7 +28,7 @@ namespace dev
 namespace solidity
 {
 
-ASTPrinter::ASTPrinter(ptr<ASTNode> _ast, std::string const& _source)
+ASTPrinter::ASTPrinter(ASTPointer<ASTNode> const& _ast, std::string const& _source)
 	: m_indentation(0), m_source(_source), m_ast(_ast)
 {
 }
diff --git a/libsolidity/ASTPrinter.h b/libsolidity/ASTPrinter.h
index 00c681f34..e8d125a54 100644
--- a/libsolidity/ASTPrinter.h
+++ b/libsolidity/ASTPrinter.h
@@ -35,7 +35,7 @@ class ASTPrinter: public ASTVisitor
 public:
 	/// Create a printer for the given abstract syntax tree. If the source is specified,
 	/// the corresponding parts of the source are printed with each node.
-	ASTPrinter(ptr<ASTNode> _ast, const std::string& _source = std::string());
+	ASTPrinter(ASTPointer<ASTNode> const& _ast, const std::string& _source = std::string());
 	/// Output the string representation of the AST to _stream.
 	void print(std::ostream& _stream);
 
@@ -108,7 +108,7 @@ private:
 
 	int m_indentation;
 	std::string m_source;
-	ptr<ASTNode> m_ast;
+	ASTPointer<ASTNode> m_ast;
 	std::ostream* m_ostream;
 };
 
diff --git a/libsolidity/NameAndTypeResolver.cpp b/libsolidity/NameAndTypeResolver.cpp
index 628d94769..84b12a238 100644
--- a/libsolidity/NameAndTypeResolver.cpp
+++ b/libsolidity/NameAndTypeResolver.cpp
@@ -42,9 +42,9 @@ void NameAndTypeResolver::resolveNamesAndTypes(ContractDefinition& _contract)
 	DeclarationRegistrationHelper registrar(m_scopes, _contract);
 	m_currentScope = &m_scopes[&_contract];
 	//@todo structs
-	for (ptr<VariableDeclaration> const& variable: _contract.getStateVariables())
+	for (ASTPointer<VariableDeclaration> const& variable: _contract.getStateVariables())
 		ReferencesResolver resolver(*variable, *this, nullptr);
-	for (ptr<FunctionDefinition> const& function: _contract.getDefinedFunctions())
+	for (ASTPointer<FunctionDefinition> const& function: _contract.getDefinedFunctions())
 	{
 		m_currentScope = &m_scopes[function.get()];
 		ReferencesResolver referencesResolver(*function, *this,
@@ -53,7 +53,7 @@ void NameAndTypeResolver::resolveNamesAndTypes(ContractDefinition& _contract)
 	// First, the parameter types of all functions need to be resolved before we can check
 	// the types, since it is possible to call functions that are only defined later
 	// in the source.
-	for (ptr<FunctionDefinition> const& function: _contract.getDefinedFunctions())
+	for (ASTPointer<FunctionDefinition> const& function: _contract.getDefinedFunctions())
 	{
 		m_currentScope = &m_scopes[function.get()];
 		function->getBody().checkTypeRequirements();
diff --git a/libsolidity/NameAndTypeResolver.h b/libsolidity/NameAndTypeResolver.h
index 076b1389f..625454566 100644
--- a/libsolidity/NameAndTypeResolver.h
+++ b/libsolidity/NameAndTypeResolver.h
@@ -23,7 +23,6 @@
 #pragma once
 
 #include <map>
-
 #include <boost/noncopyable.hpp>
 
 #include <libsolidity/Scope.h>
diff --git a/libsolidity/Parser.cpp b/libsolidity/Parser.cpp
index 4716c55df..7b1fdeb28 100644
--- a/libsolidity/Parser.cpp
+++ b/libsolidity/Parser.cpp
@@ -31,7 +31,7 @@ namespace dev
 namespace solidity
 {
 
-ptr<ContractDefinition> Parser::parse(std::shared_ptr<Scanner> const& _scanner)
+ASTPointer<ContractDefinition> Parser::parse(std::shared_ptr<Scanner> const& _scanner)
 {
 	m_scanner = _scanner;
 	return parseContractDefinition();
@@ -48,10 +48,10 @@ public:
 	void markEndPosition() { m_location.end = m_parser.getEndPosition(); }
 	void setLocationEmpty() { m_location.end = m_location.start; }
 	/// Set the end position to the one of the given node.
-	void setEndPositionFromNode(ptr<ASTNode> const& _node) { m_location.end = _node->getLocation().end; }
+	void setEndPositionFromNode(ASTPointer<ASTNode> const& _node) { m_location.end = _node->getLocation().end; }
 
 	template <class NodeType, typename... Args>
-	ptr<NodeType> createNode(Args&& ... _args)
+	ASTPointer<NodeType> createNode(Args&& ... _args)
 	{
 		if (m_location.end < 0)
 			markEndPosition();
@@ -74,15 +74,15 @@ int Parser::getEndPosition() const
 }
 
 
-ptr<ContractDefinition> Parser::parseContractDefinition()
+ASTPointer<ContractDefinition> Parser::parseContractDefinition()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::CONTRACT);
-	ptr<ASTString> name = expectIdentifierToken();
+	ASTPointer<ASTString> name = expectIdentifierToken();
 	expectToken(Token::LBRACE);
-	std::vector<ptr<StructDefinition>> structs;
-	std::vector<ptr<VariableDeclaration>> stateVariables;
-	std::vector<ptr<FunctionDefinition>> functions;
+	std::vector<ASTPointer<StructDefinition>> structs;
+	std::vector<ASTPointer<VariableDeclaration>> stateVariables;
+	std::vector<ASTPointer<FunctionDefinition>> functions;
 	bool visibilityIsPublic = true;
 	while (true)
 	{
@@ -115,19 +115,19 @@ ptr<ContractDefinition> Parser::parseContractDefinition()
 	return nodeFactory.createNode<ContractDefinition>(name, structs, stateVariables, functions);
 }
 
-ptr<FunctionDefinition> Parser::parseFunctionDefinition(bool _isPublic)
+ASTPointer<FunctionDefinition> Parser::parseFunctionDefinition(bool _isPublic)
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::FUNCTION);
-	ptr<ASTString> name(expectIdentifierToken());
-	ptr<ParameterList> parameters(parseParameterList());
+	ASTPointer<ASTString> name(expectIdentifierToken());
+	ASTPointer<ParameterList> parameters(parseParameterList());
 	bool isDeclaredConst = false;
 	if (m_scanner->getCurrentToken() == Token::CONST)
 	{
 		isDeclaredConst = true;
 		m_scanner->next();
 	}
-	ptr<ParameterList> returnParameters;
+	ASTPointer<ParameterList> returnParameters;
 	if (m_scanner->getCurrentToken() == Token::RETURNS)
 	{
 		bool const permitEmptyParameterList = false;
@@ -139,20 +139,20 @@ ptr<FunctionDefinition> Parser::parseFunctionDefinition(bool _isPublic)
 		// create an empty parameter list at a zero-length location
 		ASTNodeFactory nodeFactory(*this);
 		nodeFactory.setLocationEmpty();
-		returnParameters = nodeFactory.createNode<ParameterList>(std::vector<ptr<VariableDeclaration>>());
+		returnParameters = nodeFactory.createNode<ParameterList>(std::vector<ASTPointer<VariableDeclaration>>());
 	}
-	ptr<Block> block = parseBlock();
+	ASTPointer<Block> block = parseBlock();
 	nodeFactory.setEndPositionFromNode(block);
 	return nodeFactory.createNode<FunctionDefinition>(name, _isPublic, parameters,
 			isDeclaredConst, returnParameters, block);
 }
 
-ptr<StructDefinition> Parser::parseStructDefinition()
+ASTPointer<StructDefinition> Parser::parseStructDefinition()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::STRUCT);
-	ptr<ASTString> name = expectIdentifierToken();
-	std::vector<ptr<VariableDeclaration>> members;
+	ASTPointer<ASTString> name = expectIdentifierToken();
+	std::vector<ASTPointer<VariableDeclaration>> members;
 	expectToken(Token::LBRACE);
 	while (m_scanner->getCurrentToken() != Token::RBRACE)
 	{
@@ -165,17 +165,17 @@ ptr<StructDefinition> Parser::parseStructDefinition()
 	return nodeFactory.createNode<StructDefinition>(name, members);
 }
 
-ptr<VariableDeclaration> Parser::parseVariableDeclaration(bool _allowVar)
+ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(bool _allowVar)
 {
 	ASTNodeFactory nodeFactory(*this);
-	ptr<TypeName> type = parseTypeName(_allowVar);
+	ASTPointer<TypeName> type = parseTypeName(_allowVar);
 	nodeFactory.markEndPosition();
 	return nodeFactory.createNode<VariableDeclaration>(type, expectIdentifierToken());
 }
 
-ptr<TypeName> Parser::parseTypeName(bool _allowVar)
+ASTPointer<TypeName> Parser::parseTypeName(bool _allowVar)
 {
-	ptr<TypeName> type;
+	ASTPointer<TypeName> type;
 	Token::Value token = m_scanner->getCurrentToken();
 	if (Token::isElementaryTypeName(token))
 	{
@@ -203,28 +203,28 @@ ptr<TypeName> Parser::parseTypeName(bool _allowVar)
 	return type;
 }
 
-ptr<Mapping> Parser::parseMapping()
+ASTPointer<Mapping> Parser::parseMapping()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::MAPPING);
 	expectToken(Token::LPAREN);
 	if (!Token::isElementaryTypeName(m_scanner->getCurrentToken()))
 		throwExpectationError("Expected elementary type name for mapping key type");
-	ptr<ElementaryTypeName> keyType;
+	ASTPointer<ElementaryTypeName> keyType;
 	keyType = ASTNodeFactory(*this).createNode<ElementaryTypeName>(m_scanner->getCurrentToken());
 	m_scanner->next();
 	expectToken(Token::ARROW);
 	bool const allowVar = false;
-	ptr<TypeName> valueType = parseTypeName(allowVar);
+	ASTPointer<TypeName> valueType = parseTypeName(allowVar);
 	nodeFactory.markEndPosition();
 	expectToken(Token::RPAREN);
 	return nodeFactory.createNode<Mapping>(keyType, valueType);
 }
 
-ptr<ParameterList> Parser::parseParameterList(bool _allowEmpty)
+ASTPointer<ParameterList> Parser::parseParameterList(bool _allowEmpty)
 {
 	ASTNodeFactory nodeFactory(*this);
-	std::vector<ptr<VariableDeclaration>> parameters;
+	std::vector<ASTPointer<VariableDeclaration>> parameters;
 	expectToken(Token::LPAREN);
 	if (!_allowEmpty || m_scanner->getCurrentToken() != Token::RPAREN)
 	{
@@ -241,11 +241,11 @@ ptr<ParameterList> Parser::parseParameterList(bool _allowEmpty)
 	return nodeFactory.createNode<ParameterList>(parameters);
 }
 
-ptr<Block> Parser::parseBlock()
+ASTPointer<Block> Parser::parseBlock()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::LBRACE);
-	std::vector<ptr<Statement>> statements;
+	std::vector<ASTPointer<Statement>> statements;
 	while (m_scanner->getCurrentToken() != Token::RBRACE)
 		statements.push_back(parseStatement());
 	nodeFactory.markEndPosition();
@@ -253,9 +253,9 @@ ptr<Block> Parser::parseBlock()
 	return nodeFactory.createNode<Block>(statements);
 }
 
-ptr<Statement> Parser::parseStatement()
+ASTPointer<Statement> Parser::parseStatement()
 {
-	ptr<Statement> statement;
+	ASTPointer<Statement> statement;
 	switch (m_scanner->getCurrentToken())
 	{
 	case Token::IF:
@@ -274,7 +274,7 @@ ptr<Statement> Parser::parseStatement()
 	case Token::RETURN:
 	{
 		ASTNodeFactory nodeFactory(*this);
-		ptr<Expression> expression;
+		ASTPointer<Expression> expression;
 		if (m_scanner->next() != Token::SEMICOLON)
 		{
 			expression = parseExpression();
@@ -301,15 +301,15 @@ ptr<Statement> Parser::parseStatement()
 	return statement;
 }
 
-ptr<IfStatement> Parser::parseIfStatement()
+ASTPointer<IfStatement> Parser::parseIfStatement()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::IF);
 	expectToken(Token::LPAREN);
-	ptr<Expression> condition = parseExpression();
+	ASTPointer<Expression> condition = parseExpression();
 	expectToken(Token::RPAREN);
-	ptr<Statement> trueBody = parseStatement();
-	ptr<Statement> falseBody;
+	ASTPointer<Statement> trueBody = parseStatement();
+	ASTPointer<Statement> falseBody;
 	if (m_scanner->getCurrentToken() == Token::ELSE)
 	{
 		m_scanner->next();
@@ -321,24 +321,24 @@ ptr<IfStatement> Parser::parseIfStatement()
 	return nodeFactory.createNode<IfStatement>(condition, trueBody, falseBody);
 }
 
-ptr<WhileStatement> Parser::parseWhileStatement()
+ASTPointer<WhileStatement> Parser::parseWhileStatement()
 {
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::WHILE);
 	expectToken(Token::LPAREN);
-	ptr<Expression> condition = parseExpression();
+	ASTPointer<Expression> condition = parseExpression();
 	expectToken(Token::RPAREN);
-	ptr<Statement> body = parseStatement();
+	ASTPointer<Statement> body = parseStatement();
 	nodeFactory.setEndPositionFromNode(body);
 	return nodeFactory.createNode<WhileStatement>(condition, body);
 }
 
-ptr<VariableDefinition> Parser::parseVariableDefinition()
+ASTPointer<VariableDefinition> Parser::parseVariableDefinition()
 {
 	ASTNodeFactory nodeFactory(*this);
 	bool const allowVar = true;
-	ptr<VariableDeclaration> variable = parseVariableDeclaration(allowVar);
-	ptr<Expression> value;
+	ASTPointer<VariableDeclaration> variable = parseVariableDeclaration(allowVar);
+	ASTPointer<Expression> value;
 	if (m_scanner->getCurrentToken() == Token::ASSIGN)
 	{
 		m_scanner->next();
@@ -350,22 +350,22 @@ ptr<VariableDefinition> Parser::parseVariableDefinition()
 	return nodeFactory.createNode<VariableDefinition>(variable, value);
 }
 
-ptr<Expression> Parser::parseExpression()
+ASTPointer<Expression> Parser::parseExpression()
 {
 	ASTNodeFactory nodeFactory(*this);
-	ptr<Expression> expression = parseBinaryExpression();
+	ASTPointer<Expression> expression = parseBinaryExpression();
 	if (!Token::isAssignmentOp(m_scanner->getCurrentToken()))
 		return expression;
 	Token::Value assignmentOperator = expectAssignmentOperator();
-	ptr<Expression> rightHandSide = parseExpression();
+	ASTPointer<Expression> rightHandSide = parseExpression();
 	nodeFactory.setEndPositionFromNode(rightHandSide);
 	return nodeFactory.createNode<Assignment>(expression, assignmentOperator, rightHandSide);
 }
 
-ptr<Expression> Parser::parseBinaryExpression(int _minPrecedence)
+ASTPointer<Expression> Parser::parseBinaryExpression(int _minPrecedence)
 {
 	ASTNodeFactory nodeFactory(*this);
-	ptr<Expression> expression = parseUnaryExpression();
+	ASTPointer<Expression> expression = parseUnaryExpression();
 	int precedence = Token::precedence(m_scanner->getCurrentToken());
 	for (; precedence >= _minPrecedence; --precedence)
 	{
@@ -373,7 +373,7 @@ ptr<Expression> Parser::parseBinaryExpression(int _minPrecedence)
 		{
 			Token::Value op = m_scanner->getCurrentToken();
 			m_scanner->next();
-			ptr<Expression> right = parseBinaryExpression(precedence + 1);
+			ASTPointer<Expression> right = parseBinaryExpression(precedence + 1);
 			nodeFactory.setEndPositionFromNode(right);
 			expression = nodeFactory.createNode<BinaryOperation>(expression, op, right);
 		}
@@ -381,7 +381,7 @@ ptr<Expression> Parser::parseBinaryExpression(int _minPrecedence)
 	return expression;
 }
 
-ptr<Expression> Parser::parseUnaryExpression()
+ASTPointer<Expression> Parser::parseUnaryExpression()
 {
 	ASTNodeFactory nodeFactory(*this);
 	Token::Value token = m_scanner->getCurrentToken();
@@ -389,14 +389,14 @@ ptr<Expression> Parser::parseUnaryExpression()
 	{
 		// prefix expression
 		m_scanner->next();
-		ptr<Expression> subExpression = parseUnaryExpression();
+		ASTPointer<Expression> subExpression = parseUnaryExpression();
 		nodeFactory.setEndPositionFromNode(subExpression);
 		return nodeFactory.createNode<UnaryOperation>(token, subExpression, true);
 	}
 	else
 	{
 		// potential postfix expression
-		ptr<Expression> subExpression = parseLeftHandSideExpression();
+		ASTPointer<Expression> subExpression = parseLeftHandSideExpression();
 		token = m_scanner->getCurrentToken();
 		if (!Token::isCountOp(token))
 			return subExpression;
@@ -406,38 +406,38 @@ ptr<Expression> Parser::parseUnaryExpression()
 	}
 }
 
-ptr<Expression> Parser::parseLeftHandSideExpression()
+ASTPointer<Expression> Parser::parseLeftHandSideExpression()
 {
 	ASTNodeFactory nodeFactory(*this);
-	ptr<Expression> expression = parsePrimaryExpression();
+	ASTPointer<Expression> expression = parsePrimaryExpression();
 	while (true)
 	{
 		switch (m_scanner->getCurrentToken())
 		{
 		case Token::LBRACK:
-			{
-				m_scanner->next();
-				ptr<Expression> index = parseExpression();
-				nodeFactory.markEndPosition();
-				expectToken(Token::RBRACK);
-				expression = nodeFactory.createNode<IndexAccess>(expression, index);
-			}
+		{
+			m_scanner->next();
+			ASTPointer<Expression> index = parseExpression();
+			nodeFactory.markEndPosition();
+			expectToken(Token::RBRACK);
+			expression = nodeFactory.createNode<IndexAccess>(expression, index);
+		}
 		break;
 		case Token::PERIOD:
-			{
-				m_scanner->next();
-				nodeFactory.markEndPosition();
-				expression = nodeFactory.createNode<MemberAccess>(expression, expectIdentifierToken());
-			}
+		{
+			m_scanner->next();
+			nodeFactory.markEndPosition();
+			expression = nodeFactory.createNode<MemberAccess>(expression, expectIdentifierToken());
+		}
 		break;
 		case Token::LPAREN:
-			{
-				m_scanner->next();
-				std::vector<ptr<Expression>> arguments = parseFunctionCallArguments();
-				nodeFactory.markEndPosition();
-				expectToken(Token::RPAREN);
-				expression = nodeFactory.createNode<FunctionCall>(expression, arguments);
-			}
+		{
+			m_scanner->next();
+			std::vector<ASTPointer<Expression>> arguments = parseFunctionCallArguments();
+			nodeFactory.markEndPosition();
+			expectToken(Token::RPAREN);
+			expression = nodeFactory.createNode<FunctionCall>(expression, arguments);
+		}
 		break;
 		default:
 			return expression;
@@ -445,16 +445,16 @@ ptr<Expression> Parser::parseLeftHandSideExpression()
 	}
 }
 
-ptr<Expression> Parser::parsePrimaryExpression()
+ASTPointer<Expression> Parser::parsePrimaryExpression()
 {
 	ASTNodeFactory nodeFactory(*this);
 	Token::Value token = m_scanner->getCurrentToken();
-	ptr<Expression> expression;
+	ASTPointer<Expression> expression;
 	switch (token)
 	{
 	case Token::TRUE_LITERAL:
 	case Token::FALSE_LITERAL:
-		expression = nodeFactory.createNode<Literal>(token, ptr<ASTString>());
+		expression = nodeFactory.createNode<Literal>(token, ASTPointer<ASTString>());
 		m_scanner->next();
 		break;
 	case Token::NUMBER:
@@ -467,12 +467,12 @@ ptr<Expression> Parser::parsePrimaryExpression()
 		expression = nodeFactory.createNode<Identifier>(getLiteralAndAdvance());
 		break;
 	case Token::LPAREN:
-		{
-			m_scanner->next();
-			ptr<Expression> expression = parseExpression();
-			expectToken(Token::RPAREN);
-			return expression;
-		}
+	{
+		m_scanner->next();
+		ASTPointer<Expression> expression = parseExpression();
+		expectToken(Token::RPAREN);
+		return expression;
+	}
 	default:
 		if (Token::isElementaryTypeName(token))
 		{
@@ -483,16 +483,16 @@ ptr<Expression> Parser::parsePrimaryExpression()
 		else
 		{
 			throwExpectationError("Expected primary expression.");
-			return ptr<Expression>(); // this is not reached
+			return ASTPointer<Expression>(); // this is not reached
 		}
 		break;
 	}
 	return expression;
 }
 
-std::vector<ptr<Expression>> Parser::parseFunctionCallArguments()
+std::vector<ASTPointer<Expression>> Parser::parseFunctionCallArguments()
 {
-	std::vector<ptr<Expression>> arguments;
+	std::vector<ASTPointer<Expression>> arguments;
 	if (m_scanner->getCurrentToken() != Token::RPAREN)
 	{
 		arguments.push_back(parseExpression());
@@ -521,16 +521,16 @@ Token::Value Parser::expectAssignmentOperator()
 	return op;
 }
 
-ptr<ASTString> Parser::expectIdentifierToken()
+ASTPointer<ASTString> Parser::expectIdentifierToken()
 {
 	if (m_scanner->getCurrentToken() != Token::IDENTIFIER)
 		throwExpectationError("Expected identifier");
 	return getLiteralAndAdvance();
 }
 
-ptr<ASTString> Parser::getLiteralAndAdvance()
+ASTPointer<ASTString> Parser::getLiteralAndAdvance()
 {
-	ptr<ASTString> identifier = std::make_shared<ASTString>(m_scanner->getCurrentLiteral());
+	ASTPointer<ASTString> identifier = std::make_shared<ASTString>(m_scanner->getCurrentLiteral());
 	m_scanner->next();
 	return identifier;
 }
diff --git a/libsolidity/Parser.h b/libsolidity/Parser.h
index 2a8613216..7cc415136 100644
--- a/libsolidity/Parser.h
+++ b/libsolidity/Parser.h
@@ -34,7 +34,7 @@ class Scanner;
 class Parser
 {
 public:
-	ptr<ContractDefinition> parse(std::shared_ptr<Scanner> const& _scanner);
+	ASTPointer<ContractDefinition> parse(std::shared_ptr<Scanner> const& _scanner);
 
 private:
 	class ASTNodeFactory;
@@ -46,24 +46,24 @@ private:
 
 	/// Parsing functions for the AST nodes
 	/// @{
-	ptr<ContractDefinition> parseContractDefinition();
-	ptr<FunctionDefinition> parseFunctionDefinition(bool _isPublic);
-	ptr<StructDefinition> parseStructDefinition();
-	ptr<VariableDeclaration> parseVariableDeclaration(bool _allowVar);
-	ptr<TypeName> parseTypeName(bool _allowVar);
-	ptr<Mapping> parseMapping();
-	ptr<ParameterList> parseParameterList(bool _allowEmpty = true);
-	ptr<Block> parseBlock();
-	ptr<Statement> parseStatement();
-	ptr<IfStatement> parseIfStatement();
-	ptr<WhileStatement> parseWhileStatement();
-	ptr<VariableDefinition> parseVariableDefinition();
-	ptr<Expression> parseExpression();
-	ptr<Expression> parseBinaryExpression(int _minPrecedence = 4);
-	ptr<Expression> parseUnaryExpression();
-	ptr<Expression> parseLeftHandSideExpression();
-	ptr<Expression> parsePrimaryExpression();
-	std::vector<ptr<Expression>> parseFunctionCallArguments();
+	ASTPointer<ContractDefinition> parseContractDefinition();
+	ASTPointer<FunctionDefinition> parseFunctionDefinition(bool _isPublic);
+	ASTPointer<StructDefinition> parseStructDefinition();
+	ASTPointer<VariableDeclaration> parseVariableDeclaration(bool _allowVar);
+	ASTPointer<TypeName> parseTypeName(bool _allowVar);
+	ASTPointer<Mapping> parseMapping();
+	ASTPointer<ParameterList> parseParameterList(bool _allowEmpty = true);
+	ASTPointer<Block> parseBlock();
+	ASTPointer<Statement> parseStatement();
+	ASTPointer<IfStatement> parseIfStatement();
+	ASTPointer<WhileStatement> parseWhileStatement();
+	ASTPointer<VariableDefinition> parseVariableDefinition();
+	ASTPointer<Expression> parseExpression();
+	ASTPointer<Expression> parseBinaryExpression(int _minPrecedence = 4);
+	ASTPointer<Expression> parseUnaryExpression();
+	ASTPointer<Expression> parseLeftHandSideExpression();
+	ASTPointer<Expression> parsePrimaryExpression();
+	std::vector<ASTPointer<Expression>> parseFunctionCallArguments();
 	/// @}
 
 	/// Helper functions
@@ -71,8 +71,8 @@ private:
 	/// If current token value is not _value, throw exception otherwise advance token.
 	void expectToken(Token::Value _value);
 	Token::Value expectAssignmentOperator();
-	ptr<ASTString> expectIdentifierToken();
-	ptr<ASTString> getLiteralAndAdvance();
+	ASTPointer<ASTString> expectIdentifierToken();
+	ASTPointer<ASTString> getLiteralAndAdvance();
 	void throwExpectationError(std::string const& _description);
 	/// @}
 
diff --git a/libsolidity/Scanner.cpp b/libsolidity/Scanner.cpp
index b65c0545b..d0183db9f 100644
--- a/libsolidity/Scanner.cpp
+++ b/libsolidity/Scanner.cpp
@@ -81,12 +81,15 @@ bool IsIdentifierPart(char c)
 
 int HexValue(char c)
 {
-	if (c >= '0' && c <= '9') return c - '0';
-	else if (c >= 'a' && c <= 'f') return c - 'a' + 10;
-	else if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	else if (c >= 'a' && c <= 'f')
+		return c - 'a' + 10;
+	else if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
 	else return -1;
 }
-}
+} // end anonymous namespace
 
 Scanner::Scanner(CharStream const& _source)
 {
@@ -409,13 +412,15 @@ bool Scanner::scanEscape()
 		c = '\t';
 		break;
 	case 'u':
-		if (!scanHexNumber(c, 4)) return false;
+		if (!scanHexNumber(c, 4))
+			return false;
 		break;
 	case 'v':
 		c = '\v';
 		break;
 	case 'x':
-		if (!scanHexNumber(c, 2)) return false;
+		if (!scanHexNumber(c, 2))
+			return false;
 		break;
 	}
 
@@ -612,9 +617,8 @@ case ch:
 		int const keyword_length = sizeof(keyword) - 1;         \
 		BOOST_STATIC_ASSERT(keyword_length >= kMinLength);      \
 		BOOST_STATIC_ASSERT(keyword_length <= kMaxLength);      \
-		if (input == keyword) {                                 \
-			return token;                                         \
-		}                                                       \
+		if (input == keyword)                                   \
+			return token;                                       \
 	}
 		KEYWORDS(KEYWORD_GROUP_CASE, KEYWORD)
 	}
@@ -635,9 +639,11 @@ Token::Value Scanner::scanIdentifierOrKeyword()
 
 char CharStream::advanceAndGet()
 {
-	if (isPastEndOfInput()) return 0;
+	if (isPastEndOfInput())
+		return 0;
 	++m_pos;
-	if (isPastEndOfInput()) return 0;
+	if (isPastEndOfInput())
+		return 0;
 	return get();
 }
 
@@ -653,7 +659,8 @@ std::string CharStream::getLineAtPosition(int _position) const
 	// if _position points to \n, it returns the line before the \n
 	using size_type = std::string::size_type;
 	size_type searchStart = std::min<size_type>(m_source.size(), _position);
-	if (searchStart > 0) searchStart--;
+	if (searchStart > 0)
+		searchStart--;
 	size_type lineStart = m_source.rfind('\n', searchStart);
 	if (lineStart == std::string::npos)
 		lineStart = 0;
diff --git a/libsolidity/Scope.h b/libsolidity/Scope.h
index ced783261..2e36e5281 100644
--- a/libsolidity/Scope.h
+++ b/libsolidity/Scope.h
@@ -23,7 +23,6 @@
 #pragma once
 
 #include <map>
-
 #include <boost/noncopyable.hpp>
 
 #include <libsolidity/ASTForward.h>
diff --git a/libsolidity/Types.cpp b/libsolidity/Types.cpp
index 8ca2c6342..88abbc77d 100644
--- a/libsolidity/Types.cpp
+++ b/libsolidity/Types.cpp
@@ -28,7 +28,7 @@ namespace dev
 namespace solidity
 {
 
-ptr<Type> Type::fromElementaryTypeName(Token::Value _typeToken)
+std::shared_ptr<Type> Type::fromElementaryTypeName(Token::Value _typeToken)
 {
 	if (Token::INT <= _typeToken && _typeToken <= Token::HASH256)
 	{
@@ -52,18 +52,18 @@ ptr<Type> Type::fromElementaryTypeName(Token::Value _typeToken)
 		BOOST_ASSERT(false); // @todo add other tyes
 }
 
-ptr<Type> Type::fromUserDefinedTypeName(UserDefinedTypeName const& _typeName)
+std::shared_ptr<Type> Type::fromUserDefinedTypeName(UserDefinedTypeName const& _typeName)
 {
 	return std::make_shared<StructType>(*_typeName.getReferencedStruct());
 }
 
-ptr<Type> Type::fromMapping(Mapping const&)
+std::shared_ptr<Type> Type::fromMapping(Mapping const&)
 {
 	BOOST_ASSERT(false); //@todo not yet implemented
-	return ptr<Type>();
+	return std::shared_ptr<Type>();
 }
 
-ptr<Type> Type::forLiteral(Literal const& _literal)
+std::shared_ptr<Type> Type::forLiteral(Literal const& _literal)
 {
 	switch (_literal.getToken())
 	{
@@ -73,13 +73,13 @@ ptr<Type> Type::forLiteral(Literal const& _literal)
 	case Token::NUMBER:
 		return IntegerType::smallestTypeForLiteral(_literal.getValue());
 	case Token::STRING_LITERAL:
-		return ptr<Type>(); // @todo
+		return std::shared_ptr<Type>(); // @todo
 	default:
-		return ptr<Type>();
+		return std::shared_ptr<Type>();
 	}
 }
 
-ptr<IntegerType> IntegerType::smallestTypeForLiteral(const std::string&)
+std::shared_ptr<IntegerType> IntegerType::smallestTypeForLiteral(std::string const&)
 {
 	//@todo
 	return std::make_shared<IntegerType>(256, Modifier::UNSIGNED);
diff --git a/libsolidity/Types.h b/libsolidity/Types.h
index 9ab710942..e0c09bdcf 100644
--- a/libsolidity/Types.h
+++ b/libsolidity/Types.h
@@ -26,7 +26,7 @@
 #include <string>
 #include <boost/noncopyable.hpp>
 #include <boost/assert.hpp>
-
+#include <libsolidity/ASTForward.h>
 #include <libsolidity/Token.h>
 
 namespace dev
@@ -34,18 +34,6 @@ namespace dev
 namespace solidity
 {
 
-// AST forward declarations
-class ContractDefinition;
-class FunctionDefinition;
-class StructDefinition;
-class Literal;
-class ElementaryTypeName;
-class UserDefinedTypeName;
-class Mapping;
-
-template <typename T>
-using ptr = std::shared_ptr<T>;
-
 // @todo realMxN, string<N>, mapping
 
 class Type: private boost::noncopyable
@@ -57,11 +45,11 @@ public:
 	};
 
 	//! factory functions that convert an AST TypeName to a Type.
-	static ptr<Type> fromElementaryTypeName(Token::Value _typeToken);
-	static ptr<Type> fromUserDefinedTypeName(UserDefinedTypeName const& _typeName);
-	static ptr<Type> fromMapping(Mapping const& _typeName);
+	static std::shared_ptr<Type> fromElementaryTypeName(Token::Value _typeToken);
+	static std::shared_ptr<Type> fromUserDefinedTypeName(UserDefinedTypeName const& _typeName);
+	static std::shared_ptr<Type> fromMapping(Mapping const& _typeName);
 
-	static ptr<Type> forLiteral(Literal const& _literal);
+	static std::shared_ptr<Type> forLiteral(Literal const& _literal);
 
 	virtual Category getCategory() const = 0;
 	virtual bool isImplicitlyConvertibleTo(Type const&) const { return false; }
@@ -82,7 +70,7 @@ public:
 	};
 	virtual Category getCategory() const { return Category::INTEGER; }
 
-	static ptr<IntegerType> smallestTypeForLiteral(std::string const& _literal);
+	static std::shared_ptr<IntegerType> smallestTypeForLiteral(std::string const& _literal);
 
 	explicit IntegerType(int _bits, Modifier _modifier = Modifier::UNSIGNED);
 
@@ -95,6 +83,7 @@ public:
 	bool isHash() const { return m_modifier == Modifier::HASH || m_modifier == Modifier::ADDRESS; }
 	bool isAddress() const { return m_modifier == Modifier::ADDRESS; }
 	int isSigned() const { return m_modifier == Modifier::SIGNED; }
+
 private:
 	int m_bits;
 	Modifier m_modifier;
@@ -125,6 +114,7 @@ public:
 	virtual Category getCategory() const { return Category::CONTRACT; }
 	ContractType(ContractDefinition const& _contract): m_contract(_contract) {}
 	virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const;
+
 private:
 	ContractDefinition const& m_contract;
 };
@@ -139,6 +129,7 @@ public:
 	{
 		return _operator == Token::DELETE;
 	}
+
 private:
 	StructDefinition const& m_struct;
 };
@@ -150,6 +141,7 @@ public:
 	FunctionType(FunctionDefinition const& _function): m_function(_function) {}
 
 	FunctionDefinition const& getFunction() const { return m_function; }
+
 private:
 	FunctionDefinition const& m_function;
 };
@@ -175,11 +167,12 @@ class TypeType: public Type
 {
 public:
 	virtual Category getCategory() const { return Category::TYPE; }
-	TypeType(ptr<Type> const& _actualType): m_actualType(_actualType) {}
+	TypeType(std::shared_ptr<Type const> const& _actualType): m_actualType(_actualType) {}
+
+	std::shared_ptr<Type const> const& getActualType() const { return m_actualType; }
 
-	ptr<Type> const& getActualType() { return m_actualType; }
 private:
-	ptr<Type> m_actualType;
+	std::shared_ptr<Type const> m_actualType;
 };
 
 
diff --git a/solc/main.cpp b/solc/main.cpp
index a2b791462..e155b0fe6 100644
--- a/solc/main.cpp
+++ b/solc/main.cpp
@@ -15,9 +15,9 @@ namespace dev
 namespace solidity
 {
 
-ptr<ContractDefinition> parseAST(std::string const& _source)
+ASTPointer<ContractDefinition> parseAST(std::string const& _source)
 {
-	ptr<Scanner> scanner = std::make_shared<Scanner>(CharStream(_source));
+	ASTPointer<Scanner> scanner = std::make_shared<Scanner>(CharStream(_source));
 	Parser parser;
 	return parser.parse(scanner);
 }
@@ -73,7 +73,7 @@ int main(int argc, char** argv)
 	}
 	std::cout << "Parsing..." << std::endl;
 	// @todo catch exception
-	dev::solidity::ptr<dev::solidity::ContractDefinition> ast = dev::solidity::parseAST(src);
+	dev::solidity::ASTPointer<dev::solidity::ContractDefinition> ast = dev::solidity::parseAST(src);
 	std::cout << "Syntax tree for the contract:" << std::endl;
 	dev::solidity::ASTPrinter printer(ast, src);
 	printer.print(std::cout);
diff --git a/test/solidityNameAndTypeResolution.cpp b/test/solidityNameAndTypeResolution.cpp
index ed2cb7b53..833ae6d4b 100644
--- a/test/solidityNameAndTypeResolution.cpp
+++ b/test/solidityNameAndTypeResolution.cpp
@@ -41,7 +41,7 @@ namespace
 void parseTextAndResolveNames(const std::string& _source)
 {
 	Parser parser;
-	ptr<ContractDefinition> contract = parser.parse(
+	ASTPointer<ContractDefinition> contract = parser.parse(
 										   std::make_shared<Scanner>(CharStream(_source)));
 	NameAndTypeResolver resolver;
 	resolver.resolveNamesAndTypes(*contract);
diff --git a/test/solidityParser.cpp b/test/solidityParser.cpp
index ef434cc35..025cd74d1 100644
--- a/test/solidityParser.cpp
+++ b/test/solidityParser.cpp
@@ -37,7 +37,7 @@ namespace test
 
 namespace
 {
-ptr<ASTNode> parseText(const std::string& _source)
+ASTPointer<ASTNode> parseText(const std::string& _source)
 {
 	Parser parser;
 	return parser.parse(std::make_shared<Scanner>(CharStream(_source)));