Clojure - 编写 split-first 和 split-last 的惯用方式

Question

编写以下函数的惯用方式是什么？

(split-first #"." "abc.def.ghi") ;;=>["abc", "def.ghi"]
(split-last #"." "abc.def.ghi") ;;=>["abc.def", "ghi"]

有一个明显的（丑陋的？）解决方案使用split，但我确信有更优雅的解决方案？也许使用 regexes/indexOf/split-with ？

Answer 1

对于拆分优先，最好的方法是：

(defn split-first [re s]
  (clojure.string/split s re 2))

(split-first #"\." "abc.def.ghi") 
=> ["abc" "def.ghi"]

(split-first #"<>" "abc<>def<>ghi")
=> ["abc" "def<>ghi"]

split-last 的一种方法是使用负前瞻断言：

(defn split-last [re s]
  (let [pattern (re-pattern (str re "(?!.*" re ")"))]
    (split-first pattern s)))

(split-last #"\." "abc.def.ghi")
=> ["abc.def" "ghi"]

(split-last #"<>" "abc<>def<>ghi")
=> ["abc<>def" "ghi"]