diff options
Diffstat (limited to 'lib/kernel/date.ml')
| -rw-r--r-- | lib/kernel/date.ml | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/lib/kernel/date.ml b/lib/kernel/date.ml index 525b35b..cf5aabd 100644 --- a/lib/kernel/date.ml +++ b/lib/kernel/date.ml @@ -1,4 +1,4 @@ -type weekday = Sun | Mon | Tue | Wed | Thu | Fri | Sat +type weekday = Sun | Mon | Tue | Wed | Thu | Fri | Sat [@@deriving sexp] (* Internal representation: rata die = days since 1970-01-01 (proleptic Gregorian). Howard Hinnant's civil<->days algorithm; OCaml's `/` truncates @@ -56,3 +56,26 @@ let weekday t = (* rata 0 = 1970-01-01 = Thursday (index 4 with Sun=0). *) let w = (((t + 4) mod 7) + 7) mod 7 in [| Sun; Mon; Tue; Wed; Thu; Fri; Sat |].(w) + +let weekday_to_string = function + | Sun -> "sunday" | Mon -> "monday" | Tue -> "tuesday" | Wed -> "wednesday" + | Thu -> "thursday" | Fri -> "friday" | Sat -> "saturday" + +let to_iso8601 t = Printf.sprintf "%04d-%02d-%02d" (year t) (month t) (day t) + +let of_iso8601 s = + match String.split_on_char '-' s with + | [ y; m; d ] + when String.length y = 4 && String.length m = 2 && String.length d = 2 -> ( + match (int_of_string_opt y, int_of_string_opt m, int_of_string_opt d) with + | Some year, Some month, Some day -> make ~year ~month ~day + | _ -> Error (Printf.sprintf "date %S: not an ISO-8601 date" s)) + | _ -> Error (Printf.sprintf "date %S: expected YYYY-MM-DD" s) + +let sexp_of_t t = Sexplib0.Sexp_conv.sexp_of_string (to_iso8601 t) + +let t_of_sexp sexp = + let s = Sexplib0.Sexp_conv.string_of_sexp sexp in + match of_iso8601 s with + | Ok t -> t + | Error msg -> Sexplib0.Sexp_conv.of_sexp_error msg sexp |