关于Clojure函数参数用法，学习中一些总结，无废话，直接看代码：

一、接受不定参数

;;接受不定参数(defn f0[& pms]    (println "params count=" (count pms) " type pms=" (type pms))  (doseq [pm pms]        (println pm)    ))

;;调用示例

;;调用示例 user=> (f0 "abc" 111 :err)params count= 3  type pms= clojure.lang.ArraySeqabc111:errniluser=>

二、接受map参数，map可为空或缺失部分或全部关键字，解构出的参数值为nil

;;接受map参数，map可为空或缺失关键字，解构出的参数值为nil(defn f1[pm  {:keys [key value]}] (println "pm->" pm) (println "key->" key) (println "value->" value) )

;;调用示例

user=> (f1 "abc" {:key "kk" :value 1})pm-> abckey-> kkvalue-> 1niluser=> (f1 "abc" {:key "k2"})pm-> abckey-> k2value-> nilniluser=> (f1 "abc" {})pm-> abckey-> nilvalue-> nilniluser=>

三、接受map参数,为解构参数设置默认值

;;接受map参数,为解构参数设置默认值(defn f11[pm  {:keys [key value] :or {key "def-key" value "def-value"}}] (println "pm->" pm) (println "key->" key) (println "value->" value) )

;;调用示例

user=> (f11 "abc" {:key "kk" :value 1})pm-> abckey-> kkvalue-> 1niluser=> (f11 "abc" {:key "k2"})pm-> abckey-> k2value-> def-valueniluser=> (f11 "abc" {})pm-> abckey-> def-keyvalue-> def-valueniluser=>

四、可选命名参数

;;可选命名参数(defn f2[pm & {:keys [key value]}] (println "pm->" pm) (println "key->" key) (println "value->" value) )

;;调用示例

user=> (f2 "abc" :key "kk" :value 1)pm-> abckey-> kkvalue-> 1niluser=> (f2 "abc" :key "k2")pm-> abckey-> k2value-> nilniluser=> (f2 "abc" )pm-> abckey-> nilvalue-> nilniluser=>

五、有默认值的可选命名参数

;;有默认值的可选命名参数(defn f22[pm & {:keys [key value] :or {key "def-key" value "def-value"}} ] (println "pm->" pm) (println "key->" key) (println "value->" value) )

;;调用示例

user=> (f22 "abc" :key "kk" :value 1)pm-> abckey-> kkvalue-> 1niluser=> (f22 "abc" :key "k2")pm-> abckey-> k2value-> def-valueniluser=> (f22 "abc" )pm-> abckey-> def-keyvalue-> def-valueniluser=>