如何更新纯函数? [英] How to update pure function?

问题描述

我正在尝试执行以下操作:我想编写一个具有给定功能f的函数translate(f, c)(例如，我们知道f是单个变量x的函数)和一个常量c并返回计算f(x+c)的新函数.

I'm trying to do the following: I want to write a function translate(f, c) that takes a given function f (say we know f is a function of a single variable x) and a constant c and returns a new function that computes f(x+c).

我知道在Python函数中是一流的对象，我可以将f作为参数传递，但是我也想不出一种方法，而不必通过x，这会失败目的.

I know that in Python functions are first-class objects and that I can pass f as an argument, but I can't think of a way to do this without passing x too, which kind of defeats the purpose.

推荐答案

诀窍是让翻译返回函数 instance .

The trick is for translate to return a function instance.

def translate(f, c):
    def func(x):
        return f(x + c)
    return func

现在变量x是免费的"，并且名称f和c来自封闭的作用域.

Now the variable x is "free", and the names f and c are coming from an enclosing scope.

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