pprint.mal

;; Pretty printer a MAL object.

(def! pprint

  (let* [

    spaces- (fn* [indent]
      (if (> indent 0)
        (str " " (spaces- (- indent 1)))
        ""))

    pp-seq- (fn* [obj indent]
      (let* [xindent (+ 1 indent)]
        (apply str (pp- (first obj) 0)
                   (map (fn* [x] (str "\n" (spaces- xindent)
                                      (pp- x xindent)))
                        (rest obj)))))

    pp-map- (fn* [obj indent]
      (let* [ks (keys obj)
             kindent (+ 1 indent)
             kwidth (count (seq (str (first ks))))
             vindent (+ 1 (+ kwidth kindent))]
        (apply str (pp- (first ks) 0)
                   " "
                   (pp- (get obj (first ks)) 0)
                   (map (fn* [k] (str "\n" (spaces- kindent)
                                      (pp- k kindent)
                                      " "
                                      (pp- (get obj k) vindent)))
                        (rest (keys obj))))))

    pp- (fn* [obj indent]
      (cond
        (list? obj)   (str "(" (pp-seq- obj indent) ")")
        (vector? obj) (str "[" (pp-seq- obj indent) "]")
        (map? obj)    (str "{" (pp-map- obj indent) "}")
        :else         (pr-str obj)))

    ]

    (fn* [obj]
         (println (pp- obj 0)))))