(module (menu led)
    (enable-led
     disable-led)
  (import (scheme)
          (chicken base)
          (chicken process))

  ;; Investigate: there are the kernel modules ledtrig_timer and ledtrig_heartbeat.
  ;; The latter, when `echo heartbeat` to `trigger`, does what one would expect.
  
  (define (enable-led colour)
    (process-run (string-append "echo 255 | sudo tee /sys/class/leds/"
                                (symbol->string colour)
                                "_led/brightness")))

  (define (disable-led colour)
    (process-run (string-append "echo 0 | sudo tee /sys/class/leds/"
                                (symbol->string colour)
                                "_led/brightness"))))