package saccharine

type Node interface {
	Accept(Visitor)
}

/** ------------------------------------------------------------------------- */

type Abstraction struct {
	Parameters []string
	Body       Node
}

type Application struct {
	Abstraction Node
	Arguments   []Node
}

type Variable struct {
	Name string
}

/** ------------------------------------------------------------------------- */

func NewAbstraction(parameter []string, body Node) *Abstraction {
	return &Abstraction{Parameters: parameter, Body: body}
}

func NewApplication(abstraction Node, arguments []Node) *Application {
	return &Application{Abstraction: abstraction, Arguments: arguments}
}

func NewVariable(name string) *Variable {
	return &Variable{Name: name}
}

/** ------------------------------------------------------------------------- */

func (a *Abstraction) Accept(x Visitor) { x.VisitAbstraction(a) }
func (a *Application) Accept(x Visitor) { x.VisitApplication(a) }
func (v *Variable) Accept(x Visitor)    { x.VisitVariable(v) }

/** ------------------------------------------------------------------------- */

type Visitor interface {
	VisitAbstraction(*Abstraction)
	VisitApplication(*Application)
	VisitVariable(*Variable)
}