如何获得一个调用Java方法的Fn？ [英] How to get an Fn which calls a Java method?

问题描述

我正在学习Clojure。我写这个代码递归地走一个目录。

I'm learning Clojure. I wrote this code to recursively walk a directory.

(tree-seq #(.isDirectory %1) #(.listFiles %1) (File. "/my-directory"))

为什么不能使用 .isDirectory 作为Clojure中的第一类函数？有没有更好的方法来重写这个代码？

Why can't I use .isDirectory as a first-class function in Clojure? Is there a better way to rewrite this code?

推荐答案

Java方法不是clojure函数，因为你不能调用方法在其自己的;你必须在一个对象上调用一个方法，它必须是该方法所期望的类型的对象。换句话说，在java中，一个方法不能与其定义类完全分离（至少不能有效地）。

Java methods aren't clojure functions because you can't call a method on its own; you have to call a method on an object, and it has to be an object of the type that the method expects. In other words, in java, a method cannot be fully separated from its defining class (at least not efficiently).

＃（。foo％）的替代方法是（memfn foo），几乎没有人使用＃（...）后引入。

An alternative to #(.foo %) would be (memfn foo), which hardly anyone uses anymore after #(...) was introduced.

这篇关于如何获得一个调用Java方法的Fn？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！