Clojure 使用交换！在嵌套地图上

我将遵循《专业Clojure》一书的第6章

应用程序状态当前定义如下：

（defonce应用程序状态
（试剂/原子）
{：项目
{“aaa”
{：标题“构建鞭”
：故事
{1{：标题“为项目和故事设计数据模型”
：状态“完成”
：顺序1}
2{:title“创建故事标题输入表单”
：顺序2}
3{：标题“实现完成故事的方法”
：订单号（3}}）

我需要使用

交换

添加一个新的键值来表示一个新的故事，由一个id键入给定字段的值

（defn添加故事！[app state project id title status]；
；Q.如何使用swap！将键值对添加到：故事中？
（swap！应用程序状态更新[：projects project id:stories]assoc请务必每天学习！还有更多

我想你只需要在

(ns tst.demo.core
  (:use tupelo.core tupelo.test)
  (:require
    [clojure.string :as str]
    ))

(def state
  {:projects
   {"aaa"
    {:title   "Build Whip"
     :stories {1 {:title  "Design a data model for projects and stories"
                  :status "done"
                  :order  1}
               2 {:title "Create a story title entry form"
                  :order 2}
               3 {:title "Implement a way to finish stories"
                  :order 3}}}}})

(dotest
  (let [result (update-in state [:projects "aaa" :stories]
                 assoc 99 {:title  "Agent 99"
                           :status "foxy"
                           :order  "some-order-stuff"})
        ]
    (spyx-pretty result)))

结果：

-------------------------------
   Clojure 1.10.1    Java 13
-------------------------------

Testing tst.demo.core
result => 
{:projects
 {"aaa"
  {:title "Build Whip",
   :stories
   {1
    {:title "Design a data model for projects and stories",
     :status "done",
     :order 1},
    2   {:title "Create a story title entry form", :order 2},
    3   {:title "Implement a way to finish stories", :order 3},
    99  {:title "Agent 99", :status "foxy", :order "some-order-stuff"}}}}}

当数据位于原子内部时，解决方案几乎相同：

  (def state-atom (atom state))
  (let [result (swap! state-atom update-in [:projects "aaa" :stories]
                 assoc 99 {:title  "Agent 99"
                           :status "foxy"
                           :order  "some-order-stuff"})]
    (spyx-pretty @state-atom))

结果

(clojure.core/deref state-atom) => 
{:projects
 {"aaa"
  {:title "Build Whip",
   :stories
   {1
    {:title "Design a data model for projects and stories",
     :status "done",
     :order 1},
    2 {:title "Create a story title entry form", :order 2},
    3 {:title "Implement a way to finish stories", :order 3},
    99
    {:title "Agent 99", :status "foxy", :order "some-order-stuff"}}}}}

---

我认为您可以在本例中使用

assoc，这比
update in
简单一点，更好地描述您试图实现的目标：

(def app-state
  (atom 
   {:projects
    {"aaa"
     {:title   "Build Whip"
      :stories {1 {:title  "Design a data model for projects and stories"
                   :status "done"
                   :order  1}
                2 {:title "Create a story title entry form"
                   :order 2}
                3 {:title "Implement a way to finish stories"
                   :order 3}}}}}))

(defn unique [] (rand-int 1000000000))

(let [unique-key (unique)]
  (swap! app-state
         assoc-in
         [:projects "aaa" :stories unique-key]
         {:title  (str "Agent " unique-key)
          :status "foxy"
          :order  "some-order-stuff"}))
@app-state
;; => {:projects
;;     {"aaa"
;;      {:title "Build Whip",
;;       :stories
;;       {1 {:title "Design a data model for projects and stories", :status "done", :order 1},
;;        2 {:title "Create a story title entry form", :order 2},
;;        3 {:title "Implement a way to finish stories", :order 3},
;;        295226401 {:title "Agent 295226401", :status "foxy", :order "some-order-stuff"}}}}}


有一个输入错误，
update
实际上应该是
updatein
。