Python · Theory

Higher-order functions

Theory

104/268

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.

Diagram

def square(n):
      return n * n
         │ square(5)
         ▼
        25

Exam tip

One tiny map/filter or itertools line + output.

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.

Short notes

DefHigher-order functions works with functions or iterators.
Usemap/filter or itertools.
TrapOverusing lambda when def is clearer.

Python · Theory

Higher-order functions

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Theory

104/268

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.

Diagram

def square(n):
      return n * n
         │ square(5)
         ▼
        25

Exam tip

One tiny map/filter or itertools line + output.

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.

Short notes

DefHigher-order functions works with functions or iterators.
Usemap/filter or itertools.
TrapOverusing lambda when def is clearer.

Higher-order functions

Example

Short notes

Questions

Higher-order functions

Example

Short notes

Questions