API changes to (list-insert-at!)

This commit is contained in:
Justin Ethier 2015-05-22 01:19:03 -04:00
parent 91d8a981fb
commit a2c511a29b

View file

@ -48,9 +48,9 @@
(recur lis)) (recur lis))
;; Insert obj at index k of list, increasing length of list by one. ;; Insert obj at index k of list, increasing length of list by one.
(define (list-insert! lis k obj) (define (list-insert-at! lis obj k)
(cond (cond
((null? lis) (error "list-insert, lis cannot be null")) ((null? lis) (error "list-insert-at!, lis cannot be null"))
((and (> k 0) (null? (cdr lis))) ((and (> k 0) (null? (cdr lis)))
(set-cdr! lis (cons obj '()))) (set-cdr! lis (cons obj '())))
((zero? k) ((zero? k)
@ -58,5 +58,5 @@
(set-car! lis obj) (set-car! lis obj)
(set-cdr! lis (cons old-car (cdr lis))))) (set-cdr! lis (cons old-car (cdr lis)))))
(else (else
(list-insert! (cdr lis) (- k 1) obj)))) (list-insert-at! (cdr lis) obj (- k 1)))))