Clojure中的合并映射

我有两张以下结构的地图：

(def a {:key1 10, :key2 100})
(def b {:key1 50, :key3 10})

我想要表单的输出：

{:key1 {:val1 10, :val2 50}, 
 :key2 {:val1 100, :val2 nil}, 
 :key3 {:val1 nil, :val2: 10}}

我查看了

merge with

，但这仅在两个映射中都存在一个键时才应用函数。另一个解决方案是从两个映射中生成一组键，然后对其进行缩减以生成我想要的结构，但这感觉不是很“惯用”的Clojure

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您不需要或不希望在缺少密钥时引入显式nils。这将使源映射中的合法

nil

值与合并引入的

nil

无法区分

(get-in [:key3 :val1] merged)
;=> nil (either no value for :key3 in the map labeled :val1 or the value was nil)

(get-in [:key3 :val1] merged ::not-found)
;=> :user/not-found (this is clear here since we did not introduce any new nils)

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这几乎是重复的。我在发布之前检查了这个问题，但它与我想要的不同。

(def merged (my-merge {:val1 a, :val2 b}))

merged
;=> {:key3 {:val2 10}, :key1 {:val2 50, :val1 10}, :key2 {:val1 100}}

(get-in [:key3 :val1] merged)
;=> nil (either no value for :key3 in the map labeled :val1 or the value was nil)

(get-in [:key3 :val1] merged ::not-found)
;=> :user/not-found (this is clear here since we did not introduce any new nils)