Python := Walrus Operator in Python 3.8

Last Updated : 6 Oct, 2026

The Walrus Operator (:=), introduced in Python 3.8, allows you to assign a value to a variable as part of an expression. It helps avoid redundant code when a value needs to be both used and tested in the same expression — especially in loops or conditional statements.

Syntax

variable := expression

The expression on the right-hand side is evaluated, assigned to the variable, and then returned.

Example 1: Filtering Products Using the Walrus Operator

In this example, we use the Walrus Operator to assign the list length to a variable within the while loop condition.

Python 
products = {"Pen": 120, "Notebook": 80, "Pencil": 40}

affordable = {
    name: discounted_price
    for name, price in products.items()
    if (discounted_price := price * 0.9) < 100
}

print(affordable)

Output
{'Notebook': 72.0, 'Pencil': 36.0}

Explanation:

  • discounted_price := price * 0.9 calculates and assigns the discounted price in a single expression.
  • Condition checks whether the discounted price is below ₹100, and the same variable is reused to store the result in the dictionary.
  • This avoids calculating the discounted price separately for filtering and storing.

Example 2: Comparing with and without Walrus Operator

Here, we compare two approaches - one using the Walrus Operator and the other without it, to extract names from a list of dictionaries.

Python 
d = [
    {"userId": 1, "name": "rahul", "completed": False},
    {"userId": 1, "name": "rohit", "completed": False},
    {"userId": 1, "name": "ram", "completed": False},
    {"userId": 1, "name": "ravan", "completed": True}
]

print("With Python 3.8 Walrus Operator:")
for entry in d:
    if name := entry.get("name"):
        print(name)

print("Without Walrus operator:")
for entry in d:
    name = entry.get("name")
    if name:
        print(name)

Output
With Python 3.8 Walrus Operator:
rahul
rohit
ram
ravan
Without Walrus operator:
rahul
rohit
ram
ravan

Explanation:

  • In the first loop, name is assigned and checked in the same line using :=.
  • Second loop performs the same logic but requires two lines- assignment and condition separately.

Example 3: Simplifying User Input Loops

This example shows how the Walrus Operator can simplify continuous input loops by combining input reading and condition checking.

Without Walrus Operator

Python 
foods = []
while True:
    f = input("What food do you like?: ")
    if f == "quit":
        break
    foods.append(f)

Output

What food do you like?: apple
What food do you like?: banana
What food do you like?: quit

With Walrus Operator

Python 
foods = []
while (f := input("What food do you like? (type 'quit' to stop): ")) != "quit":
    foods.append(f)

Output

What food do you like?: apple
What food do you like?: banana
What food do you like?: quit

Explanation:

  • Input is directly assigned to food inside the while condition.
  • Loop continues until the user types 'quit', resulting in cleaner and more readable code.
Comment

Explore