ANSI Common Lisp 22 Printer 22.1 The Lisp Printer
22.1.2 Printer Dispatching
The Lisp printer makes its determination of how to print an
object as follows:
If the value of *print-pretty* is true,
printing is controlled by the current pprint dispatch table;
see Section 188.8.131.52 Pretty Print Dispatch Tables.
Otherwise (if the value of *print-pretty* is false),
the object's print-object method is used;
see Section 22.1.3 Default Print-Object Methods.