Example of chaining functions

00_README.md

All the programs below implement these steps:

1. Generate a list of 1-8, not including 8: [1, 2, 3, 4, 5, 6, 7]
2. Filter that list to even values: [2, 4, 6]
3. Return each value N repeated N times: [2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6]

01_compute-with-pydash.py

from pydash import py_


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


def repeat(n, times):
    return [n] * times


def concat(list_a, list_b):
    return [*list_a, *list_b]


def computed():
    return (
        py_(py_.range(1, 8))
        .filter(is_even)
        .map(lambda n: repeat(n, n))
        .reduce(concat, [])
        .value()
    )


print(computed())
# > python compute-with-python.py
# [2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6]

01_compute.py

from functools import reduce


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


def repeat(n, times):
    return [n] * times


def concat(list_a, list_b):
    return [*list_a, *list_b]


def computed():
    numbers = range(1, 8)
    evens = filter(is_even, numbers)
    repeats = map(lambda n: repeat(n, n), evens)
    values = reduce(concat, repeats, [])
    return values


print(computed())
# > python compute.py
# [2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6]