Higher-order functions — Python Technical Interview Questions & Answers

Higher-order functions

Higher-order functions

  • Higher-order functions is about functions that take/return functions, or itertools helpers (chain, cycle, combinations). map/filter/lambda are the fresher versions.
  • Keep it concrete: map(str.upper, ["a","b"]) → A B. itertools.chain([1],[2,3]) → 1 2 3.
  • Higher-order functions — output: 7. twice takes a function — that is higher-order.
  def square(n):
      return n * n
         │ square(5)
         ▼
        25

Technical Interview Tip: One tiny map/filter or itertools line + output.

Code Examples for Higher-order functions

Example

# Higher-order functions
def twice(fn, x):
    return fn(fn(x))
print(twice(lambda n: n + 1, 5))

Higher-order functions — output: 7. twice takes a function — that is higher-order.

How to Explain Higher-order functions to an Interviewer

Explain Higher-order functions as if you are teaching a junior — definition, then one tiny script.

Higher-order functions works with functions or iterators. map/filter or itertools.

What does the example print, and why?

Higher-order functions — output: 7

What mistake do freshers make with Higher-order functions?

Overusing lambda when def is clearer.