Linked List in crystal

list.cr

class List(T)
  
  class Node(T)
    property :value
    property :next
     
    def initialize(@value : T, @next : List::Node(T) | List::EmptyNode)
    end
  end
  
  class EmptyNode
    def value
    end
   
    def next
      self
    end
  end  
  
  def initialize
    @head = (List::EmptyNode.new).as(List::Node(T) | List::EmptyNode)
  end
  
  def prepend(value)
    new_node = List::Node(T).new(value, @head)
    @head = new_node
  end
  
  def decompose
    {@head.value, @head.next}
  end
  
  def inspect
    result = [] of String
    current = @head
    while current.class != List::EmptyNode
      result << current.value.to_s
      current = current.next
    end
    "List[" + result.join(",") + "]"
  end
  
end

list = List(Char | Int32).new
list.prepend('a')
list.prepend('b')
list.prepend('c')
list.prepend(10)
p list