sicp 1.32定义通用高阶 累积 函数

accumulate.scm

(define (accumulate combiner null-value term a next b)
    (if (> a b)
        null-value
        (combiner (term a)
           (accumulate combiner null-value term (next a) next b)
        )
    )
)

(define (accumulate combiner null-value term a next b)
    (define (iter a result)
        (if (> a b)
            result
            (iter (next a) (combiner (term a) result))
        )
    )

    (iter a null-value)
)

(define (product term a next b)
    (accumulate * 1 term a next b)
)

(define (sum term a next b)
    (accumulate + 0 term a next b)
)

和社区答案最接近的一次

高阶函数, 威力惊人

如此来看, 从 OOP 入门编程, 反倒是 遮蔽和影响了 自己业务抽象的 理解.