racket - Rotate a List of Lists -

i want take arbitrary list of lists , "rotate" it. is, list of lists of size 3x3:

#lang racket (require rackunit)  (define (rotate-lol lol)   (append (list (map first lol)) (list (map second lol)) (list (map third lol))))  (check-equal? (rotate-lol (list (list 'a 'b 'c)                                 (list 'd 'e 'f)                                 (list 'g 'h 'i)))           (list (list 'a 'd 'g)                 (list 'b 'e 'h)                 (list 'c 'f 'i))) 

i'm thinking list-ref replace first/second/third can't quite figure out concise way this.

i know there has got elegant way this. i've done inelegant solutions problem in past more domain specific, i'd solve general case, stash in personal library, , done problem. tips or solutions?

it's pretty zip , don't have make since it's in srfi-1 list library:

(require srfi/1) (zip '(a b c) '(d e f) '(g h i)) ; ==> ((a d g) (b e h) (c f i)) 

now take parameters list use apply:

(apply zip '((a b c) (d e f) (g h i))) ; ==> ((a d g) (b e h) (c f i)) 

and, completeness. here how zip defined:

(define (zip . lsts)   (apply map list lsts))