8.12
15 Formatting and Parsing
15.1 Formatting Dates and Times
procedure
t : (or/c date-provider? time-provider?) pattern : string? locale : string? = (current-locale)
Examples:
> (parameterize ([current-locale "en"]) (displayln (~t (date 1955 11 12) "E, MMMM d, y G")) (displayln (~t (datetime 1955 11 12 2 42 30) "E h:mm a")))
Sat, November 12, 1955 AD
Sat 2:42 AM
> (parameterize ([current-locale "fr"]) (displayln (~t (date 1955 11 12) "E d MMM y G")) (displayln (~t (datetime 1955 11 12 2 42 30) "E h:mm:ss a")))
sam. 12 nov. 1955 ap. J.-C.
sam. 2:42:30 AM
15.2 Parsing Dates and Times
15.2.1 Parsing ISO 8601 representations
procedure
(iso8601->date str) → date?
str : string?
Parses an ISO 8601 representation of a date into a date. Note that the input must
use the ISO 8601 extended format.
Examples:
> (iso8601->date "1981-04-05") #<date 1981-04-05>
> (iso8601->date "1981-04") #<date 1981-04-01>
procedure
(iso8601->time str) → date?
str : string?
Parses an ISO 8601 representation of a time into a time. Note that the input must
use the ISO 8601 extended format.
Example:
> (iso8601->time "13:47:30") #<time 13:47:30>
procedure
(iso8601->datetime str) → date?
str : string?
Parses an ISO 8601 combined date and time representation into a datetime. Note that
the input must use the ISO 8601 extended format.
Example:
> (iso8601->datetime "2014-03-20T19:20:09.3045") #<datetime 2014-03-20T19:20:09.3045>
procedure
(iso8601->moment str) → date?
str : string?
Parses an ISO 8601 combined date and time representation into a moment. Note that
the input must use the ISO 8601 extended format.
Example:
> (iso8601->moment "2014-03-20T19:20:09.3045Z") #<moment 2014-03-20T19:20:09.3045Z>
procedure
(iso8601/tzid->moment str) → date?
str : string?
Parses a non-standard format, consisting of an ISO 8601 combined date and time representation
and an IANA time zone ID in brackets, into a moment. The input format is the same
as that produced by moment->iso8601/tzid. Note that the ISO 8601 portion of
the input must use the ISO 8601 extended format.
Example:
> (iso8601/tzid->moment "2014-03-20T19:20:09.3045-04:00[America/New_York]") #<moment 2014-03-20T19:20:09.3045-04:00[America/New_York]>
15.2.2 Flexible parsing based on patterns
procedure
(parse-date str pattern [ #:ci? ci? #:locale locale]) → date? str : string? pattern : string? ci? : boolean? = #t locale : string? = (current-locale)
Parses str according to pattern, which uses the CLDR
pattern syntax.
The result is returned as a date. If the input cannot be parsed as a date,
exn:gregor:parse is raised.
Example:
> (parameterize ([current-locale "en"]) (list (parse-date "January 24, 1977" "LLLL d, y") (parse-date "2015-03-15T02:02:02-04:00" "yyyy-MM-dd'T'HH:mm:ssxxx"))) '(#<date 1977-01-24> #<date 2015-03-15>)
procedure
(parse-time str pattern [ #:ci? ci? #:locale locale]) → time? str : string? pattern : string? ci? : boolean? = #t locale : string? = (current-locale)
Parses str according to pattern, which uses the CLDR
pattern syntax.
The result is returned as a time. If the input cannot be parsed as a time,
exn:gregor:parse is raised.
Example:
> (parameterize ([current-locale "en"]) (list (parse-time "January 24, 1977" "LLLL d, y") (parse-time "2015-03-15T02:02:02-04:00" "yyyy-MM-dd'T'HH:mm:ssxxx"))) '(#<time 00:00:00> #<time 02:02:02>)
procedure
(parse-datetime str pattern [ #:ci? ci? #:locale locale]) → datetime? str : string? pattern : string? ci? : boolean? = #t locale : string? = (current-locale)
Parses str according to pattern, which uses the CLDR
pattern syntax.
The result is returned as a datetime. If the input cannot be parsed as a datetime,
exn:gregor:parse is raised.
Example:
> (parameterize ([current-locale "en"]) (list (parse-datetime "January 24, 1977" "LLLL d, y") (parse-datetime "2015-03-15T02:02:02-04:00" "yyyy-MM-dd'T'HH:mm:ssxxx"))) '(#<datetime 1977-01-24T00:00:00> #<datetime 2015-03-15T02:02:02>)
procedure
(parse-moment str pattern [ #:ci? ci? #:locale locale] #:resolve-offset resolve) → moment? str : string? pattern : string? ci? : boolean? = #t locale : string? = (current-locale) resolve : resolve-offset/raise
Parses str according to pattern, which uses the CLDR
pattern syntax.
The result is returned as a moment. If the input cannot be parsed as a moment,
exn:gregor:parse is raised. If the result’s UTC offset is ambigous, resolve
is used to resolve the ambiguity.
Example:
> (parameterize ([current-locale "en"] [current-timezone "Pacific/Honolulu"]) (list (parse-moment "January 24, 1977" "LLLL d, y") (parse-moment "2015-03-15T02:02:02-04:00" "yyyy-MM-dd'T'HH:mm:ssxxx")))
'(#<moment 1977-01-24T00:00:00-10:00[Pacific/Honolulu]>
#<moment 2015-03-15T02:02:02-04:00>)
parameter
→ (-> (integer-in 0 99) exact-integer?) (current-two-digit-year-resolver resolver) → void? resolver : (-> (integer-in 0 99) exact-integer?)
A parameter used to control how parsed two-digit years are resolved into complete years.
The default implementation is:
(λ (parsed-year) (define current-year (->year (now))) (define lo (- current-year 50)) (define t (if (>= lo 0) (remainder lo 100) (+ 99 (remainder (add1 lo) 100)))) (+ parsed-year lo (if (< parsed-year t) 100 0) (- t)))
Example:
> (parameterize ([current-two-digit-year-resolver (λ (y) (+ 3300 y))]) (parse-date "3/3/33" "M/d/yy")) #<date 3333-03-03>