On Sun, May 27, 2012 at 8:46 AM, Harry Spier <vasishtha.sp...@gmail.com> wrote: > (define (f1 l) > (for/fold ([result-list '()]) > ( [prior (in-list (append '() l))] > [x (in-list l)] > [next (in-list (append (rest l) '()))]) > ... > ... make new-result-element using x prior and next... > (cons new-result-element result-list)) > (reverse result-list))
If you don't need result-list in the body of the for you can use for/list which looks a bit simpler. (define (f1 l) (for/list ([prior (in-list (append '() l))] [x (in-list l)] [next (in-list (append (rest l) '()))]) ... ... make new-result-element using x prior and next...)) Cheers, Sam ____________________ Racket Users list: http://lists.racket-lang.org/users