Welcome to the CHICKEN Scheme pasting service

(use srfi-18)

(define p (make-parameter #f))

(define (finaliser x) (printf "GC of ~A.\n" x))

(define (attach-finaliser)
 (printf "Starting ~A.\n" (current-thread))
 (let ((x '(a b c)))
  (set-finalizer! (p) finaliser)
  (set-finalizer! x finaliser)
  (thread-sleep! 3)
 )
 (printf "Ending ~A.\n" (current-thread)))

(thread-start! (make-thread attach-finaliser))

(thread-sleep! 10)