#xyzzy で structure を #S(...) で出力。スロット毎に改行＋インデント。

gistfile1.cl

#+xyzzy
(defun print-structure-sharp-s-aligned (obj stream n)
  (assert (si:*structurep obj))
  (let ((def (si:*structure-definition obj)))
    (format stream "#S(~S" (si:*structure-definition-name def))
    (let ((indent (1+ (si:*stream-column stream))))
      (dotimes (i (si:*structure-definition-nslots def))
        (unless (= i 0)
          (terpri stream))
        (format stream " ~VT~S ~S"
          (if (= i 0) 0 indent)
          (si:*structure-definition-slot-description def i)
          (si:*index-slot-value obj i)))
      (format stream ")"))))

gistfile2.cl

;;; 試してみる

(defstruct (something
            (:print-function print-structure-sharp-s-aligned))
  foo bar baz)
=> #<structure-definition: something>

(print-structure-sharp-s-aligned
 (make-something :foo 33 :bar (make-hash-table) :baz (cons nil nil))
 *standard-output*
 1)
#S(something :foo 33
             :bar #<hashtable 82317844>
             :baz (nil))