问题
If I define a function that returns a function like this:
(defn add-n
[n]
(fn [x] (+ x n)))
I can then assign the result to a symbol:
(def add-1 (add-n 1))
and call it:
(add-1 41)
;=> 42
How do I call the result of (add-n 1) without assigning it to a new symbol? The following produces this output:
(println (add-n 1))
#<user$add_n$fn__33 user$add_n$fn__33@e9ac0f5>
nil
The #<user$add_n$fn__33 user$add_n$fn__33@e9ac0f5> is an internal reference to the generated function.
回答1:
Easy:
(println ((add-n 1) 41))
The output you saw is a function definition. Putting it between round brackets and adding a parameter is enough to call it.
来源：https://stackoverflow.com/questions/6008775/calling-clojure-higher-order-functions