a cute CAT ^-^ in common lisp

cat.lisp

(defmacro cat
    ((&key (to nil)
           (trim '())
           prefix
           postfix)
     &body form#list-of-list)
  (let* ((form#list-of-list#2
          (apply (function append)
                 (mapcar (lambda (list)
                           (list prefix
                                 (list 'string-trim trim
                                       (append '(format nil) list))
                                 postfix))
                         form#list-of-list)))
         (form#final (append '(concatenate (quote string))
                             form#list-of-list#2)))
    `(let ((string-for-return ,form#final))
       (format ,to "~A" string-for-return)
       string-for-return)))


(cat (:to *standard-output*
          :trim '(#\Space)
          :prefix "* "
          :postfix (cat () ("~%")))
  ("~A" "  123   ")
  ("~A" " 456  "))