FWPD，Clojure for the Brave and True的僵尸数据分析程序

Question

我正在尝试理解“勇敢与真实的Clojure”这本书第四章末尾的程序“一个FWPD的僵尸数据分析程序”。代码如下：

(ns fwpd.core)

(def filename "suspects.csv")

(def vamp-keys [:name :glitter-index])

(defn str->int
  [str]
  (Integer. str))

(def conversions {:name identity
              :glitter-index str->int})

(defn convert
   [vamp-key value]
  ((get conversions vamp-key) value))

(defn parse
  "Convert a CSV into rows of columns"
  [string]
  (map #(clojure.string/split % #",")
   (clojure.string/split string #"\n")))

(defn mapify
  "Return a seq of maps like {:name \"Edward Cullen\" :glitter-index 10}"
  [rows]
 (map (fn [unmapped-row]
     (reduce (fn [row-map [vamp-key value]]
               (assoc row-map vamp-key (convert vamp-key value)))
             {}
             (map vector vamp-keys unmapped-row)))
   rows))

(defn glitter-filter
  [minimum-glitter records]
  (filter #(>= (:glitter-index %) minimum-glitter) records))

有人能帮我讲讲转换和转换函数吗？