(import (chicken process signal))
(import srfi-18)

(define (make-handler cv msg)
  (lambda (signum)
    (print msg " signal")
    (condition-variable-specific-set! cv 'break)
    (condition-variable-signal! cv)))

(let [(m (make-mutex))
      (cv (make-condition-variable))]
  (condition-variable-specific-set! cv 'hold)
  (set-signal-handler! signal/int (make-handler cv "INT"))
  (thread-start! (lambda ()
                   (sleep 4)
                   (condition-variable-specific-set! cv 'break)
                   (condition-variable-signal! cv)))
  (let loop ()
    (print "+ loop")
    (mutex-lock! m)
    (print "+ unlock")
    (mutex-unlock! m cv)
    (when (equal? 'hold (condition-variable-specific cv))
      (loop))
    (print "done")))