声明Clojure匿名函数的虚拟(未使用)参数 [英] Declare dummy (unused) parameters for Clojure anonymous function

问题描述

也如该问题的答案中所述，Clojure通过主体中引用的最大参数索引(例如，如果最大引用的参数为%4，则该匿名函数具有4个值)来确定匿名函数的参数数量(通过#()定义).参数).

As also explained in the answers of this question, Clojure determines the number of parameters of an anonymous function (defined through #()), by the maximal parameter index referenced in the body (e.g. if the maximal referenced parameter is %4, then that anonymous function has 4 parameters).

问题:是否有一些语法告诉Clojure编译器匿名函数需要一个参数，甚至没有引用该参数?或者，在这种情况下，唯一的干净方法" *是使用 fn语法? (*干净的方式":我知道在大多数情况下，您可以引用哑参数而不影响功能-参见下文，但我想避免此类解决方法.)

Question: is there some syntax to tell the Clojure compiler that an anonymous function expects one parameter, even not referencing that parameter? Or, in this case, the only "clean way"* is to use the fn syntax? (* "Clean way": I'm aware that in most cases, you could reference the dummy parameter without affecting the function -- see below, but I would like to avoid such workarounds.)

我的用例:我有一个函数(defn foo [predicate])，其中predicate恰好期望一个参数，并且我想用始终返回true的谓词测试foo. (即类似#(true)的东西.)这会导致产生ArityException，因为解释器认为#(true)期望参数为零.

My use case: I have a function (defn foo [predicate]), where predicate expects exactly one argument, and I would like to test foo with a predicate that always returns true. (I.e., something like #(true).) This causes an ArityException since the interpreter thinks that #(true) expects zero arguments.

在这种情况下，我可以使用诸如#(or true %)这样的聪明技巧，但是:

In this particular case, I could use some clever hack like #(or true %), but:

1. 键入的内容几乎与fn变体相同.
2. 我对是否有通用解决方案感兴趣.

1. It is almost as much to type as the fn-variant.
2. I'm interested if there is a generic solution.

为清楚起见，我正在寻找类似这样的内容:

so to be clear, I'm looking for something like this:

#[1](true) ;; the anonymous function takes one parameter

推荐答案

否.只需使用fn.那就是它的目的.

No. Just use fn. That's what it's for.

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