From Newsgroup: comp.lang.lisp

Frank Buss wrote:

How to read a comma separated list from a file.
For example, " 2, 3, 5, 6,".

I assume you want to read only one line, every item is an integer and
empty entries should be ignored (after your last comma). Here is a
recursive solution:

(defun split (string delimiter)
(when (= 0 (length delimiter)) (error "delimiter length = 0"))
(let ((start (search delimiter string)))
(if (not start)
(if (= 0 (length string))
nil
(list string))
(let ((value (string-trim '(#\Space) (subseq string 0 start)))
(rest (subseq string (+ start (length delimiter)))))
(if (= 0 (length value))
(split rest delimiter)
(cons value (split rest delimiter)))))))

Gauche Scheme

After converting all of the commas to spaces, repeatedly
read from the string and put the numbers into a list
(using the seldom seen "unfold").

(use srfi-1) ;; unfold

(with-input-from-string
(string-map (lambda(c) (if (eq? c #\,) #\space c)) " 2, 3, 5, 6,")
(lambda()
(unfold eof-object? identity (lambda _ (read)) (read))))

===>
(2 3 5 6)
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