如何使Clojure函数取可变数量的参数？ [英] How to make a Clojure function take a variable number of parameters?

问题描述

我正在学习Clojure，我试图定义一个函数，它接受可变数量的参数（一个可变参数函数）并将它们求和（yep，就像+过程）。但我不知道如何实现这样的功能。

I'm learning Clojure and I'm trying to define a function that take a variable number of parameters (a variadic function) and sum them up (yep, just like the + procedure). However, I don´t know how to implement such function

我可以做的一切是：

（defn sum [n1，n2]（+ n1 n2））

当然这个函数有两个参数和两个参数只要。

Of course this function takes two parameteres and two parameters only. Please teach me how to make it accept (and process) an undefined number of parameters.

推荐答案

一般来说，非交换的情况下您可以使用套用：

In general, non-commutative case you can use apply:

(defn sum [& args] (apply + args))

由于添加是可交换的，这样的东西也应该可以工作：

Since addition is commutative, something like this should work too:

(defn sum [& args] (reduce + args))

& c $ c> args 绑定到参数列表的其余部分（在这种情况下是整个列表，因为& ）。

& causes args to be bound to the remainder of the argument list (in this case the whole list, as there's nothing to the left of &).

显然，定义这样的和没有意义，因为代替：

Obviously defining sum like that doesn't make sense, since instead of:

(sum a b c d e ...)

/ p>

you can just write:

(+ a b c d e ....)

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