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Functions & basics

Reusable building blocks — parameters, returns, scope, and clear function design.

5 matches

How to Compose Two Functions into a Single Callable in Python

Combine two Python functions into a single callable using a compose helper, then apply the chained call.

def add_one(x):
    return x + 1

def double(x):
    return x * 2

def compose(f, g):
    return lambda x: f(g(x))

add_then_double = compose(double, add_one)
double_then_add = compose(add_one, double)

result1 = add_then_double(5)
result2 = double_then_add(5)

print(f"add_one then double(5) = {result1}")
print(f"doub…

12 0 Open

Functions & basics medium

How to Implement a Trampoline for Tail Recursion in Python

This code implements a trampoline decorator that converts tail-recursive functions into iterative loops, allowing deep recursion without hitting Python's recursion limit.

trampoline tail-recursion decorator

Python

def trampoline(fn):
    """Convert a tail-recursive function into an iterative loop."""
    def wrapper(*args, **kwargs):
        result = fn(*args, **kwargs)
        while callable(result):
            result = result()
        return result
    return wrapper

@trampoline
def factorial(n, acc=1):
    """Tail-recursi…

11 0 Open

Functions & basics easy

How to Pass a Function as a Callback to map and filter in Python

Shows how to apply custom functions to every element of a list using map and filter callbacks in Python.

map filter callbacks

Python

def double(x):
    return x * 2

def is_even(x):
    return x % 2 == 0

if __name__ == "__main__":
    numbers = [1, 2, 3, 4, 5]
    doubled = list(map(double, numbers))
    evens = list(filter(is_even, numbers))
    print("Original:", numbers)
    print("Doubled:", doubled)
    print("Evens:", evens)

16 0 Open

Functions & basics easy

How to Pipe Data Through a List of Transform Functions in Python

Applies a sequence of functions to an initial value using functools.reduce, creating a reusable pipe utility.

functions functional reduce

Python

from functools import reduce

def pipe(data, *transforms):
    return reduce(lambda value, func: func(value), transforms, data)

def double(x):
    return x * 2

def add_one(x):
    return x + 1

def to_string(x):
    return f"Result: {x}"

if __name__ == "__main__":
    initial = 5
    result = pipe(initial, double, …

13 0 Open

Functions & basics easy

How to Use functools.reduce in Python

Apply functools.reduce with operator functions and lambda expressions to aggregate lists into sums, products, maximums, and concatenated strings.

reduce functools lambda

Python

from functools import reduce
import operator

# Sum all numbers in a list using reduce
numbers = [1, 2, 3, 4, 5]
sum_result = reduce(operator.add, numbers)

# Find the maximum value using reduce
max_result = reduce(lambda a, b: a if a > b else b, numbers)

# Multiply all numbers using reduce
product_result = reduce(la…

12 0 Open

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