Edi Weitz wrote:

> I wanted to write a function that reads whitespace-separated numbers
> from a string, i.e. given a string like "1 2 3 4" I wanted my function
> to return the list (1 2 3 4).
>
> Two different solutions came to mind:
>
> (defun foo1 (string)
> (loop for start = 0 then pos
> for (object pos) = (multiple-value-list
> (read-from-string string nil nil :start start))
> while object
> collect object))
>
> (defun foo2 (string)
> (let ((start 0) object result)
> (loop
> (multiple-value-setq (object start)
> (read-from-string string nil nil :start start))
> (unless object
> (return-from foo2 (nreverse result)))
> (push object result))))

Gauche Scheme and Racket:

;; For Racket only.
(require srfi/26) ;; cut

(define (read-em)
(define x (read))
(if (eof-object? x) '() (cons x (read-em))))

(with-input-from-string "2 3 4 5" (cut read-em))

===>
(2 3 4 5)