Clojure:有没有人制作过可视化代码树结构的工具？

Question

我正在学习 Clojure(我的第一个 LISP)并学习 LISP 固有的“代码即数据”的想法可视化工具中的语法树 - 可能是宏扩展前后？

我指的是用类似 SVG 的方式对树进行图形描述。

Answer 1

真的，你所要做的就是' (quote)一种获取它的 AST 的形式。这就是 lisp 的美妙之处。假设您有标准的 every? 函数:

(defn every?
  "Returns true if (pred x) is logical true for every x in coll, else
   false."
  {:tag Boolean
   :added "1.0"
   :static true}
  [pred coll]
  (cond
     (nil? (seq coll)) true
     (pred (first coll)) (recur pred (next coll))
     :else false))

只要引用它就可以得到一个嵌套的符号列表:

; Notice the quote at the start!
'(defn every?
   "Returns true if (pred x) is logical true for every x in coll, else
   false."
   {:tag Boolean
    :added "1.0"
    :static true}
   [pred coll]
   (cond
      (nil? (seq coll)) true
      (pred (first coll)) (recur pred (next coll))
      :else false))
=>
(defn
 every?
 "Returns true if (pred x) is logical true for every x in coll, else\nfalse."
 {:tag Boolean, :added "1.0", :static true}
 [pred coll]
 (cond (nil? (seq coll)) true (pred (first coll)) (recur pred (next coll)) :else false))

您可以使用标准的 clojure.pprint/pprint 函数(缩进表示嵌套)将其整理一下以便可视化:

(clojure.pprint/pprint
  '(defn every?
     "Returns true if (pred x) is logical true for every x in coll, else
   false."
     {:tag Boolean
      :added "1.0"
      :static true}
     [pred coll]
     (cond
        (nil? (seq coll)) true
        (pred (first coll)) (recur pred (next coll))
        :else false)))
(defn
 every?
 "Returns true if (pred x) is logical true for every x in coll, else\n   false."
 {:tag Boolean, :added "1.0", :static true}
 [pred coll]
 (cond
  (nil? (seq coll))
  true
  (pred (first coll))
  (recur pred (next coll))
  :else
  false))

并且您可以通过调用 macroexpand 来获得后宏扩展表示:

(clojure.pprint/pprint
  (macroexpand
    '(defn every?
       "Returns true if (pred x) is logical true for every x in coll, else
   false."
       {:tag Boolean
        :added "1.0"
        :static true}
       [pred coll]
       (cond
          (nil? (seq coll)) true
          (pred (first coll)) (recur pred (next coll))
          :else false))))
(def
 every?
 (clojure.core/fn
  ([pred coll]
   (cond
    (nil? (seq coll))
    true
    (pred (first coll))
    (recur pred (next coll))
    :else
    false))))

如果您正在寻找比这更多的东西，引用一些代码然后递归地搜索它是微不足道的。您可以将其更改为您想要的任何格式。