Functional Programming in Python

Lambda Functions

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LearnStep 1 of 3

Anonymous Functions in Action

Learning Objectives

•Understand the syntax and purpose of lambda functions in Python
•Apply lambda functions as arguments to higher-order functions like sorted, map, and filter
•Recognize the readability trade-offs and limitations of lambda expressions
•Utilize the operator module as a cleaner alternative to common lambda patterns

Lesson Outline

LearnStep 1/3

Anonymous Functions in Action

In Python, lambda functions are small, anonymous functions defined with the lambda keyword. Unlike functions defined with def, lambdas are expressions, meaning they yield a function object directly. They are restricted to a single expression; they cannot contain statements or annotations.

Syntax

The syntax is lambda arguments: expression. The expression is evaluated and returned. They are most idiomatic when used as throwaway functions for callbacks or key functions.

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Common Use Cases

Lambdas shine when passed as arguments to higher-order functions like sorted(), map(), and filter().

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Readability Limits

While concise, lambdas can hurt readability if they become complex. Python's style guide (PEP 8) discourages assigning lambdas to variables (use def instead). If a lambda expression barely fits on one line, it should probably be a named function.

The Operator Module

For simple operations like retrieving an item or attribute, the operator module is often faster and more readable than a lambda.

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