Question

我在一本书（Scala和Clojure中的函数式编程模式）中找到了以下代码。 for语句使用close-zip？过滤掉拉链外的人，然后它会给剩下的人带来问候。但是，我不太确定人们应该如何看待generate-greetings和print-greetings函数的论点？

(def close-zip? #{19123 19103})

(defn generate-greetings [people]
  (for [{:keys [name address]} people :when (close-zip? (address :zip-code))]
    (str "Hello, " name ", and welcome to the Lambda Bar And Grille!")))

(defn print-greetings [people]
  (doseq [{:keys [name address]} people :when (close-zip? (address :zip-code))]
    (println (str "Hello, " name ", and welcome to the Lambda Bar And Grille!"))))

Answer 1

他们需要使用:name和:address键映射，例如：

{:name "A Person", :address {:zip-code 19103}}

for将从people中获取每个元素并将每个元素分配给{:keys [name address]}。这称为destructuring，这只是一种便利。这跟说：

(for [person people
      :let [name (:name person)
            address (:address person)]
      :when (close-zip? (:zip-code address))]
  (str ...))

序列理解得到运行

1 个答案: