;; date.scm

(import srfi-19 chicken.format)
(let* ((today (current-date))
       (yesterday (date-subtract-duration today (make-duration days: 1))))
  (printf "~A ~A ~A\n"
          today
          (if (date<? today yesterday) "<" ">")
          yesterday)
  (printf "~A ~A ~A\n"
          today
          (if (date>? today yesterday) ">" "<")
          yesterday))

;; csi -s date.scm
#@2023-01-28T19:15:08Z < #@2023-01-27T19:15:08Z
#@2023-01-28T19:15:08Z < #@2023-01-27T19:15:08Z