Welcome to the CHICKEN Scheme pasting service

(import (chicken format))
(require-extension coops)

(define-record-printer (coops-instance obj out)
  (handle-exceptions ex
      (begin
        (display "#<no print-method defined for: " out)
        (default-print-method obj out)
        (display ">" out))
    (print-object obj out) ) )

(define-class <test> ())

(define-method (print-object (obj <test>) #!optional (out (current-output-port)))
  (format out "#<test>"))

(print (make <test>))