Reduce-strings Join adjacent strings in a list, leave other values intact.

reduce-strings.lisp

;; Took from postmodern's s-sql.lisp
 
(defun reduce-strings (list)
  "Join adjacent strings in a list, leave other values intact."
  (let ((accum ())
        (span ""))
    (dolist (part list)
      (cond ((stringp part) (setf span (concatenate 'string span part)))
            (t (when (not (string= "" span))
                 (push span accum)
                 (setf span ""))
               (push part accum))))
    (if (not (string= "" span))
        (push span accum))
    (nreverse accum)))