Higher Order Function

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Introduction to Higher-Order Functions

In Python, a higher-order function is a function that can accept another function as an argument or return a function as its result. This is possible because Python treats functions as first-class citizens, meaning functions behave like regular objects.

As a result, functions can be:

• Assigned to variables
• Passed as parameters
• Returned from other functions
• Stored in data structures

This capability makes Python well-suited for functional programming concepts.

Why Higher-Order Functions Matter

Higher-order functions allow you to:

• Write generic and reusable code
• Separate what to do from how to do it
• Avoid writing multiple similar functions
• Dynamically change behavior by passing different functions

Instead of writing separate logic for squaring, cubing, or other operations, a single higher-order function can handle all cases.

Basic Example: Passing a Function as an Argument

A function can receive another function as a parameter and execute it dynamically.

def square(num):
    return num * num

def cube(num):
    return num * num * num

def operate(num, operation):
    return operation(num)

value = 5
result = operate(value, square)
print(result)

Output:

25

Here:

• operate is a higher-order function
• square is passed as an argument
• operation(num) dynamically executes the passed function

Changing the behavior requires no change to the higher-order function:

result = operate(value, cube)
print(result)

Output:

125

Higher-Order Function with Multiple Values

Higher-order functions can also process collections of data.

def square(num):
    return num * num

def cube(num):
    return num * num * num

def operate(nums, operation):
    for i in nums:
        print(operation(i))

nums = [5, 6, 7]
operate(nums, cube)

Output:

125
216
343

Here:

• A list of values is passed
• The same function works for any operation
• Only the behavior changes, not the structure of the code

Key Characteristics

• The higher-order function does not care about the logic of the operation
• It only knows when and how to call the passed function
• This enables abstraction and flexibility

Real-World Use Cases

Higher-order functions are widely used in:

• Data transformation pipelines
• Callback functions
• Event handling
• Functional utilities
• Clean and scalable code design

Summary

• Higher-order functions accept other functions as arguments.
• They rely on Python’s first-class function support.
• They enable abstraction, flexibility, and code reuse.
• The behavior can be changed dynamically without modifying core logic.
• Commonly used in functional programming and real-world applications.