opaque-tzinfo.rkt

#lang racket

(require soft-contract/fake-contract)

(struct tzgap (starts-at offset-before offset-after) #:transparent)
(struct tzoffset (utc-seconds dst? abbreviation) #:transparent)
(struct tzoverlap (offset-before offset-after) #:transparent)

(define tz? (or/c string? exact-integer?))
(define system-tzid #:opaque)
(define local-seconds->tzoffset #:opaque)
(define utc-seconds->tzoffset #:opaque)

(provide
 (contract-out
  [system-tzid (-> (or/c #f tz?))]
  [struct tzgap ([starts-at exact-nonnegative-integer?]
                 [offset-before tzoffset?]
                 [offset-after tzoffset?])]
  [struct tzoffset ([utc-seconds exact-integer?]
                    [dst? boolean?]
                    [abbreviation string?])]
  [struct tzoverlap ([offset-before tzoffset?]
                     [offset-after tzoffset?])]
  [local-seconds->tzoffset (-> string? exact-integer? (or/c tzoffset? tzgap? tzoverlap?))]
  [utc-seconds->tzoffset (-> string? (and/c rational? exact?) tzoffset?)]))