# reduce.py -rw-r--r-- 680 bytes View raw 
                                                                                
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from typing import Callable


def reduce(function, accumulator, items):
    if len(items) == 0:
        return accumulator
    return reduce(function, function(accumulator, items[0]), items[1:])


def reduce(function, accumulator, items):
    match items:
        case []:
            return accumulator
        case [head, *tail]:
            return reduce(function, function(accumulator, head), tail)


type Reducer = Callable[[A, B], A]


def reduce[A, B](function: Reducer, accumulator: A, items: list[B]) -> A:
    match items:
        case []:
            return accumulator
        case [head, *tail]:
            return reduce(function, function(accumulator, head), tail)