(use-modules (ice-9 control))
;; (use shift-reset)
(let ((captured-k
       (reset (display (shift f f)))))
  (display
   (string-append
    "str: '"
    (with-output-to-string
      (lambda ()
        (captured-k "this should go to the string")))
    "'")))

;; $ csi -qbn tesu.rkt        
;; this should go to the stringstr: ''

;; $ guile tesu.rkt           
;; str: 'this should go to the string'