clojure-函数体或let语句中的defn/def

Question

user=> (defn make-list [] '(1 2 3))
#'user/make-list
user=> (defn get-list [] (map #(str "foo" % ) make-list))
#'user/get-list
user=> (get-list)
IllegalArgumentException Don't know how to create ISeq from: user$make-list  clojure.lang.RT.seqFrom (RT.java:505)
user=> (defn get-list [] (let [ml (make-list)] (map #(str "foo" % ) ml) ))
#'user/get-list
user=> (get-list)
("foo1" "foo2" "foo3")

为什么defn中的值不能以与LET子句相同的方式从函数体中访问？

Answer 1

defn声明一个函数，因此需要调用它才能得到结果：

(defn make-list [] '(1 2 3))
(defn get-list [] (map #(str "foo" % ) (make-list)))
(get-list)

;; ("foo1" "foo2" "foo3")

但是由于您的makeList函数只返回一个列表，所以您可以使用def，因为它只是声明了一个变量：

(def make-list '(1 2 3))
(defn get-list [] (map #(str "foo" % ) make-list))
(get-list)

;;("foo1" "foo2" "foo3")

最后，在Clojure中使用kebab case而不是camelCase作为函数和变量名。这是惯例，除非你在声明协议或类型。