Join

Adam Warner wrote:

Hi Lowell Kirsh,
 

I want to write a function to take a list of strings and a delimiter and
return a string with the strings put together with the delimiter as glue.

 

e.g. (join '("foo" "bar" "baz")) -> "foo:bar:baz"

 
(defun join (list &optional (delimiter #\:))
  (let ((countdown (length list)))
    (with-output-to-string (stream)
      (dolist (item list)
        (write-string item stream)
        (decf countdown)
        (unless (zerop countdown)
          (write-char delimiter stream))))))

Gauche Scheme

(define (join lst :optional (delimiter #\,))
  (with-output-to-string
    (lambda()
      (display (car lst))
      (for-each
        (cut format #t "~a~a" delimiter <>)
        (cdr lst)))))