Paradigms

Functional programming

we can make this more ... aesthetically pleasing
decompose our operation into single steps that do exactly one thing
- filter the list
- square the elements
- sum the list

evenQ = lambda x : x % 2 == 0
square1 = lambda x : x**2
tally = lambda x, y : x + y

square_and_sum = lambda lst : reduce(tally, map(square1, filter(evenQ, lst)))

is this better? who knows..
it’s easier too debug though since evenQ just does ONE thing without side effects