Yesterday I was printing text in my condition handling + restarts example, when (print condition) actually works with :report as detailed here.
https://screwlisp.small-web.org/fundamental/common-lisp-conditions-using-report/
#programming #commonLisp condition handling. #prettyprinting
CL-USER> (make-condition 'foo :format-arguments '(1 2 3))
#<FOO "With arguments ~@{~a~^, ~}" {100215BF33}>
CL-USER> (princ *)
With arguments 1, 2, 3
#<FOO "With arguments ~@{~a~^, ~}" {100215BF33}>
CL-USER> (prin1 *)
#<FOO "With arguments ~@{~a~^, ~}" {100215BF33}>