Python 编写高阶归约

def s0(data: Sequence) -> float:
    return sum(1 for x in data) # or len(data)
def s1(data: Sequence) -> float:
    return sum(x for x in data) # or sum(data)
def s2(data: Sequence) -> float:
    return sum(x * x for x in data)

from typing import Callable, Iterable, Any
def sum_f(
        function: Callable[[Any], float],
        data: Iterable) -> float:
    return sum(function(x) for x in data)

N = sum_f(lambda x: 1, data) # x ** 0
S = sum_f(lambda x: x, data) # x ** 1
S2 = sum_f(lambda x: x * x, data) # x ** 2

def sum_filter_f(
        filter_f: Callable,
        function: Callable, data: Iterable) -> Iterator:
    return sum(function(x) for x in data if filter_f(x))

count_ = lambda x: 1
sum_ = lambda x: x
valid = lambda x: x is not None
N = sum_filter_f(valid, count_, data)