为什么地图和关键字都带有一个额外的默认参数,而集合却没有?
这是实现细节还是具体设计决策呢?
这是实现细节还是具体设计决策呢?
({:a 2} :b :not-found) ;;=> :not-found
(:b {:a 2} :not-found) ;;=> :not-found
;; This seems counter intuitive.
(#{:a} :b :not-found) ;;=> clojure.lang.ArityException
(:b #{:a} :not-found) ;;=> :not-found