Program

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The function reduce-left.

Lecture 4 - slide 16 : 34
Program 2

(define (reduce-left f lst)
  (reduce-help-left f (cdr lst) (car lst)))

(define (reduce-help-left f lst res)
  (if (null? lst)
      res
      (reduce-help-left f (cdr lst) (f res (car lst)))))