question9

gistfile1.txt

(define (sub-all s olds news)
    (define (helper val)
        (define (final-val val old-vals new-vals)
            (if (null? old-vals)
                val
                (if (eq? val (car old-vals))
                    (car new-vals)
                    (final-val val (cdr old-vals) (cdr new-vals))
                )
            )
        )
        (if (list? val)
            (map helper val)
            (final-val val olds news)
        )
    )
    (map helper s)
)