[plt-scheme] looping?

Mike wrote:
> I know there is intended a lot of recursion for scheme,
> but is there looping? The REPL construct isn't recursive
> (my guess). How do you loop?
>
> (define *running* #t)
> (while *running*
>   (if (something-is-done)
>     (set! *running* #f)))
>
>   
let loop comes to mind

(let loop ((x 2)
                (y "fred"))
   (unless (something-is-done)
        (loop x y)))