+(defun riece-ruby-substitute-variables (program alist)
+ "Substitute symbols in PROGRAM by looking up ALIST.
+Return a string concatenating elements in PROGRAM."
+ (setq program (copy-sequence program))
+ (while alist
+ (let ((pointer program))
+ (while pointer
+ (setq pointer (memq (car (car alist)) program))
+ (if pointer
+ (setcar pointer (cdr (car alist))))))
+ (setq alist (cdr alist)))
+ (apply #'concat program))
+