Replaces the first target in replace-list that matches in string at pos with its replacement. See also repl-substring-list?.
(define (repl-substring-list string replace-list pos)
  ;; Replace the first target in the replacement list that matches
  (if (repl-substring-list? string replace-list pos)
      (let ((target (repl-substring-list-target string replace-list pos))
	    (repl   (repl-substring-list-repl string replace-list pos)))
	(repl-substring string target repl pos))
      string))