有条件地添加到集合中(Conditionally adding to a collection)

我想根据条件向集合中添加一些东西，否则就不管它了。

我发现自己写的是这样的：

(defn make-zoo
  [zoo has-ice]
  (let [zoo (if has-ice (conj zoo "penguins") zoo)]
    zoo))

(make-zoo ["tigers"] false) ;["tigers"] 
(make-zoo ["polar bears"] true) ;["polar bears" "penguins"]
 
 我对Clojure很陌生，但对于常见的操作来说，这似乎是一个笨重的解决方案。 有更优雅的方式来解决这个问题吗？ 
I want to add something to a collection based on a condition and leave it alone otherwise.
 
I found myself writing something like this:
 
(defn make-zoo
  [zoo has-ice]
  (let [zoo (if has-ice (conj zoo "penguins") zoo)]
    zoo))

(make-zoo ["tigers"] false) ;["tigers"] 
(make-zoo ["polar bears"] true) ;["polar bears" "penguins"]
 
I'm pretty new to Clojure, but this seems like a clunky solution for a common operation. Is there a more elegant way to address this?
                
最满意答案
                
                    
                        
 我们可以使用cond-> macro来简化make-zoo ，它是->线程宏的条件派生词： 
 
(defn make-zoo [zoo has-ice]
  (cond-> zoo, has-ice (conj "penguins")))
We can simplify make-zoo using the cond-> macro, a conditional derivative of the -> threading macro:
 
(defn make-zoo [zoo has-ice]
  (cond-> zoo, has-ice (conj "penguins")))