Clojure：更新记录字段的值

我已定义记录来存储用户详细信息和地址详细信息。

(defrecord User [id name address])

(defrecord Address [id location street city state])

(def usr (User. 1 "Abc"
           (Address. 1 "Location 1" "Street" "NY" "US")))

我已使用以下代码将“名称”更新为“BCD”

(assoc usr :name "BCD")

Output:

#async_tea_party.core.User{:id 1, :name "BCD", :address #async_tea_party.core.Address{:id 1, :location "Location 1", :street "Street", :city "NY", :state "US"}}

(usr)

OutPut:

#async_tea_party.core.User{:id 1, :name "Abc", :address #async_tea_party.core.Address{:id 1, :location "Location 1", :street "Street", :city "NY", :state "US"}}

新值name字段尚未更新，它仍然显示旧值。

如何永久更新“用户”记录中的“姓名”字段？

(def usr (User...))是一种一成不变的。你无法改变它。 当你这样做时(assoc usr :name "BCD")你没有改变它。你创建一个新的。为了做你想做的事，你需要一个原子。

(def usr (atom (User. 1 "Abc"
           (Address. 1 "Location 1" "Street" "NY" "US"))))

(:name @usr) ;; "Abc"
(swap! usr assoc :name "BCD")
(:name @usr) ;; "BCD"