(xml-seq root)
返回一个惰性序列，序列里包含一棵 xml 元素树。
xml 文件可以用 clojure.xml/parse 函数解释。
; 解释一个 xml 文件，并提取内容
user=> (require 'clojure.xml)
nil
user=> (def content (clojure.xml/parse "http://www.w3schools.com/xml/note.xml"))
#'user/content
; 根据 xml 内容，生成 xml 树
user=> (def tree (xml-seq content))
#'user/tree
user=> tree
({:tag :note, :attrs nil, :content [{:tag :to, :attrs nil, :content ["Tove"]} {:tag :from, :attrs nil, :content ["Jani"]} {:tag :heading, :attrs nil, :content ["Reminder"]} {:tag :body, :attrs nil, :content ["Don't forget me this weekend!"]}]} {:tag :to, :attrs nil, :content ["Tove"]} "Tove" {:tag :from, :attrs nil, :content ["Jani"]} "Jani" {:tag :heading, :attrs nil, :content ["Reminder"]} "Reminder" {:tag :body, :attrs nil, :content ["Don't forget me this weekend!"]} "Don't forget me this weekend!")
; 遍历树
user=> (nth tree 0)
{:tag :note, :attrs nil, :content [{:tag :to, :attrs nil, :content ["Tove"]} {:tag :from, :attrs nil, :content ["Jani"]} {:tag :heading, :attrs nil, :content ["Reminder"]} {:tag :body, :attrs nil, :content ["Don't forget me this weekend!"]}]}
user=> (nth tree 1)
{:tag :to, :attrs nil, :content ["Tove"]}
user=> (nth tree 2)
"Tove"
user=> (nth tree 3)
{:tag :from, :attrs nil, :content ["Jani"]}
user=> (nth tree 4)
"Jani"