Copyright	(C) 2013 Jann Mueller
License	BSD3 (see the file LICENSE)
Maintainer	j.mueller.11@ucl.ac.uk
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Data.Time.Patterns

Contents

Date Patterns
- Months
- Days
Operations on date patterns
Queries

Description

Patterns for recurring events. Use the DatePattern type to build up a pattern, and the functions elementOf, instancesFrom and intervalsFrom to evaluate it. Simple example:

import Control.Lens
import Data.Thyme.Calendar
import Data.Time.Patterns
import qualified Prelude as P
Module Main where

main = do
  -- get the 6th of April for the next ten years
  let april6 = (take 1 $ skip 5 day) `inEach` april
  let today = (YearMonthDay 2013 12 01)^.from gregorian
  print $ P.take 10 $ instancesFrom today april6

DatePatterns can be combined using union, intersect with their obvious meanings and inEach which repeats one pattern inside another one. For example,

((take 1 day) `inEach` august) `intersect` sunday

will give the 1st of August in years when it falls on a Sunday.

Synopsis

Date Patterns

type DatePattern = IntervalSequence' Day Source

A DatePattern describes a sequence of intervals of type Data.Thyme.Day.

day :: DatePattern Source

An event that occurs every day.

mondayWeek :: DatePattern Source

Weeks, starting on Monday

sundayWeek :: DatePattern Source

Weeks, starting on Sunday.

month :: DatePattern Source

An event that occurs every month.

year :: DatePattern Source

Years, starting from Jan. 1

Months

january :: DatePattern Source

Every January.

february :: DatePattern Source

Every February.

march :: DatePattern Source

Every March.

april :: DatePattern Source

Every April.

may :: DatePattern Source

Every May.

june :: DatePattern Source

Every June.

july :: DatePattern Source

Every July.

august :: DatePattern Source

Every August.

september :: DatePattern Source

Every September.

october :: DatePattern Source

Every October.

november :: DatePattern Source

Every November.

december :: DatePattern Source

Every December.

Days

monday :: DatePattern Source

Every Monday.

tuesday :: DatePattern Source

Every Tuesday.

wednesday :: DatePattern Source

Every Wednesday.

thursday :: DatePattern Source

Every Thursday.

friday :: DatePattern Source

Every Friday.

saturday :: DatePattern Source

Every Saturday.

sunday :: DatePattern Source

Every Sunday.

Operations on date patterns

never :: DatePattern Source

An event that never occurs

every :: (Num i, Ord i) => i -> DatePattern -> DatePattern Source

Take every nth occurrence

shiftBy :: Days -> DatePattern -> DatePattern Source

Shift all the results by a number of day

inEach :: DatePattern -> DatePattern -> DatePattern Source

The first pattern repeated for each interval of the second pattern. E.g.:

(take 3 $ every 4 monday) `inEach` year

will give the fourth, eighth and twelveth Monday in each year

take :: (Num i, Ord i) => i -> DatePattern -> DatePattern Source

Stop after n occurrences

skip :: (Num i, Ord i) => i -> DatePattern -> DatePattern Source

Skip the first n occurrences

except :: Day -> DatePattern -> DatePattern Source

Skip over all occurrences of a day. If the pattern describes a period longer than a day, the entire period will be skipped.

intersect :: DatePattern -> DatePattern -> DatePattern Source

Return only occurrences that are present in both patterns

let myBirthday = (take 1 day) `inEach` august
let s = intersect myBirthday sunday

Will return August 1 in years when it falls on a Sunday

union :: DatePattern -> DatePattern -> DatePattern Source

Occurrences of both patterns.

union april june

Will return the months April and June in each year

let fifteenth = (take 1 $ skip 14 day) `inEach` month
let third = (take 1 $ skip 2 day) `inEach` month
union fifteenth third

Will return the 3rd and the 15th of each month

Queries

elementOf :: Day -> DatePattern -> Bool Source

Check if a date is covered by a DatePattern

instancesFrom :: Day -> DatePattern -> [Day] Source

Get occurrences of an event starting with a given day

intervalsFrom :: Day -> DatePattern -> [Interval Day] Source

Get the date intervals described by the pattern, starting from the specified date.

The intervals range from the first day included by the pattern to the first day after it, so a single day d would be described as (d ... succ d) and the interval for a month will go from the 1st of the month to the 1st of the next month.