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Module Schedule

ERROR: schedule.mli:9:6-9:8
9:6-9:8 :
nested '{v'

Signature

ERROR: schedule.mli:45:2-45:4
14:2-14:4 :
unterminated '{v'

Daylight Savings Time

Schedules are expressed in terms of wall clock time, and as such have interesting behavior around daylight savings time boundaries. There are two circumstances that might affect a schedule. The first is a repeated time, which occurs when time jumps back (e.g. 2:30 may happen twice in one day). The second is a skipped time, which occurs when time jumps forward by an hour.

In both cases Schedule does the naive thing. If the time happens twice and is included in the schedule it is included twice. If it never happens Schedule makes no special attempt to artificially include it.

type zoned =
| Zoned

these phantom types are concrete and exposed to help the compiler understand that zoned and unzoned cannot be the same type (which it could not know if they were abstract), which helps it infer the injectivity of the type t below.

type unzoned =
| Unzoned
  • In_zone: see the discussion under Zones and Tags above
  • Tag: see the discussion under Zones and Tags above
  • And, Or, Not: correspond to the set operations intersection, union, and complement.
  • If_then_else (A, B, C): corresponds to (A && B) || (NOT A && C), useful for dealing with schedules that change during certain times of the year (holidays, etc.)
  • At : the exact times given on every day
  • Shift : shifts an entire schedule forward or backwards by a known span. (e.g:
  • Shift ((sec 3.), Secs[10]) = Secs [13]
  • Shift ((sec (-3.)), Secs[10]) = Secs [7])
  • Between : the contiguous range between the start and end times given on every day
  • Secs : the exact seconds given during every hour of every day
  • Mins : all seconds in the minutes given during every hour of every day
  • Hours : all seconds in the hours given on every day
  • Weekdays : all seconds in the days given on every week
  • Days : all seconds in the days given, every month
  • Weeks : all seconds in the weeks given (numbered ISO 8601), every year
  • Months : all seconds in the months given, every year
  • On : all seconds in the exact dates given
  • Before : all seconds before the given boundary (inclusive or exclusive)
  • After : all seconds after the given boundary (inclusive or exclusive)
  • Always : the set of all seconds
  • Never : the empty set

'a indicates whether the schedule currently has an established zone.

'b is the type of the tag used in this schedule. In many cases it can be unspecified. See tags for more.

Between (a, b) is the empty set if a > b.

Items that take int lists silently ignore ints outside of the viable range. E.g. Days [32] will never occur.

module Inclusive_exclusive : sig .. end
type ('a, 'b) t =
| In_zone : Time.Zone.t * (unzoned, 'b) t -> (zoned, 'b) t
| Tag : 'b * ('a, 'b) t -> ('a, 'b) t
| And : ('a, 'b) t list -> ('a, 'b) t
| Or : ('a, 'b) t list -> ('a, 'b) t
| Not : ('a, 'b) t -> ('a, 'b) t
| If_then_else : (('a, 'b) t * ('a, 'b) t * ('a, 'b) t) -> ('a, 'b) t
| Shift : Time.Span.t * ('a, 'b) t -> ('a, 'b) t
| At : Time.Ofday.t list -> (unzoned, 'b) t
| Secs : int list -> (unzoned, 'b) t
| Mins : int list -> (unzoned, 'b) t
| Hours : int list -> (unzoned, 'b) t
| Weekdays : Core_kernel.Std.Day_of_week.t list -> (unzoned, 'b) t
| Days : int list -> (unzoned, 'b) t
| Weeks : int list -> (unzoned, 'b) t
| Months : Core_kernel.Std.Month.t list -> (unzoned, 'b) t
| On : Date.t list -> (unzoned, 'b) t
| Before : (Inclusive_exclusive.t * (Date.t * Time.Ofday.t)) -> (unzoned, 'b) t
| After : (Inclusive_exclusive.t * (Date.t * Time.Ofday.t)) -> (unzoned, 'b) t
| Always : ('a, 'b) t
| Never : ('a, 'b) t
val compare : ('b -> 'b -> int) -> ('a, 'b) t -> ('a, 'b) t -> int
val to_string_zoned : (zoned, 'b) t -> string_of_tag:('b -> string) -> string

Return a string suitable for debugging purposes.

module Stable : sig .. end
val includes : (zoned, 'b) t -> Time.t -> bool

includes t time is true if the second represented by time falls within the schedule t.

val tags : (zoned, 'tag) t -> Time.t -> [
| `Not_included
| `Included of 'tag list
]

tags t time = `Not_included iff not (includes t time). Otherwise, tags t time = `Included lst , where lst includes all tags of a schedule such that includes t' time is true where t' is a tagged branch of the schedule. E.g. for some t equal to Tag some_tag t', tags t time will return some_tag if and only if includes t' time returns true. For a more interesting use case, consider the per-office on-call schedule example given in the beginning of this module. Note that a schdeule may have no tags, and therefore, lst can be empty.

val all_tags : (zoned, 'tag) t -> tag_comparator:('tag, 'cmp) Core_kernel.Std.Comparator.t -> ('tag, 'cmp) Core_kernel.Std.Set.t
val fold_tags : (zoned, 'tag) t -> init:'m -> f:('m -> 'tag -> 'm) -> Time.t -> 'm option

fold_tags t ~init ~f time is nearly behaviorally equivalent to (but more efficient than) List.fold ~init ~f (tags t time), with the exception that it returns None if includes t time is false. It is important that f be pure, as its results may be discarded.

val map_tags : ('a, 'b) t -> f:('b -> 'c) -> ('a, 'c) t

Return a sequence of schedule changes over time that will never end.

If your schedules ends, you will continue to receive `No_change_until_at_least with increasing times forever.

The return type indicates whether includes t start_time is true and delivers a sequence of subsequent changes over time.

The times returned by the sequence are strictly increasing and never less than start_time. That is, `No_change_until_at_least x can never be followed by `Enter x, only by (at least) `Enter (x + 1s).

if emit is set to Transitions_and_tag_changes then all changes in tags will be present in the resulting sequence. Otherwise only the tags in effect when a schedule is entered are available.

The `In_range | `Out_of_range flag in `No_change_until_at_least indicates whether the covered range is entirely within, or outside of the time covered by the schedule and is only there to help with bookkeeping for the caller. `In_range | `Out_of_range will never disagree with what could be inferred from the `Enter and `Leave events.

The sequence takes care to do only a small amount of work between each element, so that pulling the next element of the sequence is always cheap. This is the primary motivation behind including `No_change_until_at_least.

The Time.t returned by `No_change_until_at_least is guaranteed to be a reasonable amount of time in the future (at least 1 hour).

module Event : sig .. end
type ('tag, 'a) emit =
| Transitions : ('tag, [
| Event.no_change
| 'tag Event.transition
]) emit
| Transitions_and_tag_changes : ('tag -> 'tag -> bool) -> ('tag, [
| Event.no_change
| 'tag Event.transition
| 'tag Event.tag_change
]) emit

in Transitions_and_tag_changes equality for the tag type must be given

val to_endless_sequence : (zoned, 'tag) t -> start_time:Time.t -> emit:('tag, 'a) emit -> [
| `Started_in_range of 'tag list * 'a Core_kernel.Std.Sequence.t
| `Started_out_of_range of 'a Core_kernel.Std.Sequence.t
]
val next_enter_between : (zoned, 'tag) t -> Time.t -> Time.t -> Time.t option

next_enter_between t start end The given start end range is inclusive on both ends. This function is useful for one-off events during the run of a program. If you want to track changes to a schedule over time it is better to call to_endless_sequence

val next_leave_between : (zoned, 'tag) t -> Time.t -> Time.t -> Time.t option

as next_enter_between but for leave events