XPost: comp.lang.scheme

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))))

Scheme

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

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

===>
(2 3 4 5)

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