hanging-read pasted by Lattay on Wed Mar 25 16:40:59 2020

(import chicken.process)

(define-values (in out pid err) (process* "rev"))

(write ":abc\n" out)
(display (read-char in))

no title added by megane on Wed Mar 25 17:46:23 2020

(import chicken.process)

(define-values (in out pid err) (process* "rev"))

(close-input-port err)
(let lp ()
  (if (char-ready? in)
      (display (read-char in))
      (display "abc\n" out))
  (lp))