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First Class functions in Python

  • Difficulty Level : Medium
  • Last Updated : 25 Nov, 2020

First class objects in a language are handled uniformly throughout. They may be stored in data structures, passed as arguments, or used in control structures. A programming language is said to support first-class functions if it treats functions as first-class objects. Python supports the concept of First Class functions.

Properties of first class functions:

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  • A function is an instance of the Object type.
  • You can store the function in a variable.
  • You can pass the function as a parameter to another function.
  • You can return the function from a function.
  • You can store them in data structures such as hash tables, lists, …

Examples illustrating First Class functions in Python

1. Functions are objects: Python functions are first class objects. In the example below, we are assigning function to a variable. This assignment doesn’t call the function. It takes the function object referenced by shout and creates a second name pointing to it, yell.

# Python program to illustrate functions
# can be treated as objects
def shout(text):
    return text.upper()
print (shout('Hello'))
yell = shout
print (yell('Hello'))



2. Functions can be passed as arguments to other functions: Because functions are objects we can pass them as arguments to other functions. Functions that can accept other functions as arguments are also called higher-order functions. In the example below, we have created a function greet which takes a function as an argument.

# Python program to illustrate functions
# can be passed as arguments to other functions
def shout(text):
    return text.upper()
def whisper(text):
    return text.lower()
def greet(func):
    # storing the function in a variable
    greeting = func("""Hi, I am created by a function
                    passed as an argument.""")
    print (greeting) 


hi, i am created by a function passed as an argument.

3. Functions can return another function: Because functions are objects we can return a function from another function. In the below example, the create_adder function returns adder function.

# Python program to illustrate functions
# Functions can return another function
def create_adder(x):
    def adder(y):
        return x+y
    return adder
add_15 = create_adder(15)
print (add_15(10))



This article is contributed by Mayank Agrawal. If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

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