在Clojure中将对象包装到集合中的惯用方式(如果还不是集合)? [英] Idiomatic way to wrap object into collection (if it's not a collection already) in Clojure?

问题描述

例如，我有多种数据结构，例如 {:name"Peter":children"Mark"} 和 {:name"Mark":children ["Julia" John] 即:children的值可以是单个字符串或字符串集合.我代码中的其他函数期望:children的值始终是字符串的集合，因此我需要为其修改数据.
当然，我可以使用类似的东西:

I have (for instance) a mix of data structures such as {:name "Peter" :children "Mark"} and {:name "Mark" :children ["Julia" "John"] i.e. :children value is either a single string or a collection of strings. Other functions in my code expect that the value of :children is always a collection of strings, so I need to adapt the data for them.
Of course I can use something like:

(defn data-adapter [m]
  (let [children (:children m)]
    (assoc m :children 
             (if (coll? children) 
               children
               [children]))))

但是还有一种惯用/简洁的方法吗?

But is there a more idiomatic/laconic way?

推荐答案

我认为您不必回答.

(if(coll?x)x [x])尽可能简洁明了.这就是人们通常用来解决此问题的方式(有时使用 sequential?而不是 coll?).

(if (coll? x) x [x]) is about as terse and expressive as it gets. It’s what people usually use for this problem (sometimes with sequential? instead of coll?).

cond-> 爱好者有时会尝试使用它来代替一个简单的条件，但是在这里并没有改善:

cond-> enthusiasts like me sometimes try to use it in place of a simple conditional, but here it is no improvement:

(cond-> x (not (coll? x)) vector)

但是，在代码的上下文中，您可以做得更好.查找和关联最好用 update :

In the context of your code, however, you can do a little better. A lookup and association is best expressed with update:

(defn data-adapter [m]
  (update m :children #(if (coll? %) % [%])))

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