11 lines
380 B
Text
11 lines
380 B
Text
(define (insert-after lst target item)
|
|
(when (null? lst) (error "cannot insert in" null))
|
|
(let [(sub-list (member target lst))]
|
|
(if sub-list (set-cdr! sub-list (cons item (cdr sub-list))) ; make chirurgy if found
|
|
(nconc lst item)))) ; else append item
|
|
|
|
(define L '(a b))
|
|
(insert-after L 'a 'c)
|
|
L → (a c b)
|
|
(insert-after L 'x 'y)
|
|
L → (a c b y)
|