为什么Clojure的地图破坏看起来逆转？ [英] Why does Clojure's map destructuring look reversed?

问题描述

解构地图与我相反。任何人都可以解释发生了什么？

我期望这是正确的解构地图形式

; =>（let [{：aa：bb} {：a 1：b 2}] [ab]）

$ b b

返回异常不支持的绑定形式：：clojure.core / destructure / pb - 4541（core.clj：4029）。 Clojure的文档说，下面是正确的方法。

b

; =>（let [{a：ab：b} {：a 1：b 2}] [ab]）
[1 2]

解构地图时会发生什么？

解决方案

实际上它是有道理的。它说：将符号'a'绑定到与关键字相关联的值：a

当你的地图使用关键字作为键时，你知道这一点吗？

 （let [{：keys [ab]} {：a 1：b 2}] [ab]）
  

非常整洁优雅！

符号或字符串。

Destructuring a map looks reversed to me. Can anybody explain what is happening?

I expect that this is the right form of destructuring a map

;=> (let [{:a a :b b} {:a 1 :b 2}] [a b])

which returns Exception Unsupported binding form: :a clojure.core/destructure/pb--4541 (core.clj:4029). Clojure documentations say that below is the right way. But it looks that keys and values are reversed.

This should be the right way:

;=> (let [{a :a b :b} {:a 1 :b 2}] [a b]) [1 2]

What is happening when destructuring a map?

解决方案

It is not really reversed, actually it makes sense. It says: bind to symbol 'a' to value that is associated with the keyword :a

Are you aware of this when your map uses keywords as keys?

(let [{:keys [a b]} {:a 1 :b 2}] [a b])

Much neater and elegant!

Other variants exist if your keys are symbols or strings.

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