class Hamster::Stack

def clear 

def clear
  EmptyStack
end

def empty? 

def empty?
  @list.empty?
end

def eql?(other) 

def eql?(other)
  instance_of?(other.class) && @list.eql?(other.instance_variable_get(:@list))
end

def initialize 

def initialize
  @list = EmptyList
end

def inspect 

def inspect
  @list.inspect
end

def peek 

def peek
  @list.head
end

def pop 

def pop
  list = @list.tail
  if list.empty?
    EmptyStack
  else
    transform { @list = list }
  end
end

def push(item) 

def push(item)
  transform { @list = @list.cons(item) }
end

def size 

def size
  @list.size
end

def to_a 

def to_a
  @list.to_a
end

def to_ary 

def to_ary
  @list.to_ary
end