Closures and Higher-Order Functions

Closures and Higher-Order Functions

In this lesson — part of Advanced Features — you'll learn closures and higher-order functions in Python and why it matters in real work.

Why it matters

Functions that take or return functions unlock concise, composable code.

Key ideas

• Functions as values
• map / filter / reduce
• Callbacks
• Composition

In practice

Here's how it looks in idiomatic Python:

nums = [1, 2, 3, 4, 5, 6]
evens = filter(lambda n: n % 2 == 0, nums)
squares = list(map(lambda n: n * n, evens))
print(squares)  # [4, 16, 36]

Python note: map() and filter() return lazy iterators, so wrap them in list(); many Pythonistas prefer a comprehension like [n*n for n in nums if n%2==0].

Try it yourself

Exercise: In Python, use map and filter to get the squares of the even numbers.

Recap

You now understand closures and higher-order functions and can apply it in Python. Mark this lesson complete and continue to the next one.