The generic function print-object writes the printed representation of object to stream . In addition, each implementation must provide methods on enough other classes so as to ensure that there is always an applicable method .
Implementations are free to add methods for other classes .
Pretty Print Dispatch Tables and Section 22.2.2 Examples of using the Pretty Printer . Examples of using the Pretty Printer . If these rules are not obeyed, the results are undefined. In some implementations the stream argument passed to a print-object method is not the original stream , but is an intermediate stream that implements part of the printer.