Re: Illegal LOOP usage?

Edi Weitz wrote:

So, this function from Drakma
 
  (defun split-string (string &optional (separators " ,-"))
    "Splits STRING into substrings separated by the characters in the
  sequence SEPARATORS.  Empty substrings aren't collected."
    (loop for char across string
          when (find char separators :test #'char=)
          when collector
          collect (coerce collector 'string) into result
          and do (setq collector nil) end
          else
          collect char into collector
          finally (return (if collector
                            (append result (list (coerce collector 'string)))
                            result))))
 
works as intended with LispWorks, but doesn't work with AllegroCL or
SBCL.  It seems the latter two simply ignore the (SETQ COLLECTOR NIL)
form.  My guess is that the code above is somehow incorrect in that it
modifies a variable which is used in a "collect ... into ..." clause,
but I couldn't find anything in the CLHS that explicitly says so.
 
Any hints?

Gauche Scheme

(use srfi-13)  ;; string-tokenize
(use srfi-14)  ;; character sets

(define (split-string strng :optional (separators " ,-"))
  (define good-chars
    (char-set-complement (string->char-set separators)))
  (string-tokenize strng good-chars))

(split-string " foo   bar-baz--zoo,,sooth,,,")
  ===>
("foo" "bar" "baz" "zoo" "sooth")

(split-string " foo   bar-baz--zoo,,sooth,,,"  " o")
  ===>
("f" "bar-baz--z" ",,s" "th,,,")