Solution to SICP Exercise 1.32

; part a (recursive process)


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

  (if (> a b)

      null-value

      (combiner (term a)

         (accumulate-r combiner null-value term (next a) next b))))
(define (sum-r term a next b)

  (accumulate-r + 0 term a next b))
(define (product-r term a next b)

  (accumulate-r * 1 term a next b))
; part b (iterative process)

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

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