What are the syntax and structure characteristics of lambda expressions?

Lambda expression is an anonymous function without a name, and its syntax is: (parameter_list) -> expression. They feature anonymity, diversity, currying, and closure. In practical applications, lambda expressions can be used to succinctly define functions, such as the summation function sum_lambda = lambda x, y: x y, and apply the map() function to the list to perform the summation operation.

The syntax and structure of Lambda expressions

Introduction

Lambda expressions are anonymous functions that provide A concise way to define functions and pass them to other code or store them in variables. Their simplicity makes them very useful in functional programming and stream processing.

Grammar

lambda expression has the following syntax:

(parameter_list) -> expression

• parameter_list: The parameter list of the function, which can Contains multiple parameters.
• ->: Lambda operator, separates the parameter list from the expression.
• expression: Function body, returns the value of expression.

Structure

Lambda expression has the following structure:

• Header part: consists of parameter list and Lambda operator.
• Body part: It consists of an expression and returns the value of the function.

Features

Lambda expressions have the following characteristics:

• Anonymity: No explicitness Function names make the code more concise.
• Diversity: Can accept different parameters and return different value types.
• Currying: You can convert a multi-parameter Lambda expression into a set of single-parameter Lambda expressions.
• Closure: Can access variables in its definition scope.

Practical case

Consider the following code:

# 创建一个以两个数字为参数并返回其和的 lambda 表达式
sum_lambda = lambda x, y: x + y

# 使用 lambda 表达式对列表求和
numbers = [1, 2, 3, 4, 5]
total = sum(map(sum_lambda, numbers))

print(total)  # 输出：15

In this example, sum_lambda is a lambda expression Formula, which accepts two parameters x and y and returns their sum. The map() function uses the sum_lambda expression to sum each element in the numbers list, and finally the sum() function sums these The sums are added to get the final sum 15.

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