Recall the example from lecture, when we first saw accumulators:
;; bounced-a-check?: lon --> bool
;; given a list of bank transaction and an initial bank balance,
;; tell whether a check might bounce.
;; (A positive transaction means a deposit.)
;;
(define bounced?
(lambda (bal transacts)
(cond [(empty? transacts) (negative? bal)]
[else (or (negative? bal)
(bounced? (+ bal (first transacts)) (rest
transacts)))])))
This example is a better accumulator example than sum-acc,
because it doesn't have an easy non-accumulator version.