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

问题描述

我正在学习 Clojure，我正在尝试定义一个函数，该函数接受可变数量的参数(一个 variadic 函数)并将它们相加(是的，就像 + 过程一样).但是，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

我能做的就是:

(defn sum [n1, n2] (+ n1 n2))

当然这个函数只需要两个参数和两个参数.请教我如何让它接受(和处理)未定义数量的参数.

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

一般情况下，非交换情况可以使用 apply:

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

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

由于加法是可交换的，这样的事情也应该起作用:

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

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

& 导致 args 被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 &).

显然这样定义 sum 没有意义，因为不是:

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

(sum a b c d e ...)

你可以写:

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

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