(define ((mapping f) f1)
  (lambda (input result)
    (f1 (f input) result)))

(define ((filtering pred) combine)
  (lambda (input result)
    (if (pred input)
        (combine input result) result)))


(fold ((mapping add1) cons) (list)   (iota 10))
(fold ((mapping add1) +) 0 (iota 10))

(fold ((filtering odd?) cons) (list) (iota 10))