伯克利 CS61A 课堂笔记 03 —— Higher-Order Functions

本系列为加州伯克利大学著名 Python 基础课程 CS61A 的课堂笔记整理，全英文内容，文末附词汇解释。

目录

01 Higher-Order Functions

01-1 Functions as Argument Values

01-2 Functions as Return Values

02 Environments of Higher-Order Functions

03 Lambda Expressions

04 What Would Python Print

附：词汇解释

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01 Higher-Order Functions

A function that takes a function as an argument value or returns a function as a return value.

① Express general methods of computation

② Remove repetition(重复) from programs

③ Separate concerns among functions

01-1 Functions as Argument Values

"""Generalization."""

from math import pi, sqrt

def area_square(r):
    return r * r

def area_circle(r):
    return r * r * pi

def area_hexagon(r):
    return r * r * 3 * sqrt(3) / 2

"""Generalize Formal Paraments."""

from math import pi, sqrt

def area(r, shape_constant):
    assert r > 0, 'A length must be positive'
    return r * r * shape_constant ※

def area_square(r):
    return area(r, 1)

def area_circle(r):
    return area(r, pi)

def area_hexagon(r):
    return area(r, 3 * sqrt(3) / 2)

"""Generalize Functions"""

def natural(k):
    return k

def cube(k):
    return pow(k, 3)

def pi_term(k):
    return 8 / mul(4 * k - 3, a * k - 1)

def summation(n, term):
    """Sum the first n terms of a sequence.
    >>> summation(5, cube)
    225
    """
    
    total, k = 0, 1
    while k <= n:
        total,