elm-time

elm package install elm-community/elm-time

Major Changes!

This release prepares elm-time to be upgraded to Elm 0.19 by changing out the ISO8601 and Timezone Name parsing from the parser-combinators parser to Evan's parser.

NOTE: this release is probably the last Elm 0.18 release.

Hence, the changes are extensive and some API's have changed. Here's a summary of them:

• ISO8601 processing has been broken out into its own module: Time.Iso8601.
• An "Elm-style" error renderer for ISO8601 parsing errors is provided: Time.Iso8601ErrorMsg.
• An example Elm client-application showing the error handling is provided in /examples/with-parser-error-renderer.
• Each of the public APIs in Time.Date, Time.DateTime, Time.ZonedDateTime, Iso8601, and Iso8601ErrorMsg now has extensive "verify examples" documentation.

Examples

• Error Rendering Example
• Running and Understanding Timezone Examples

Dates

Dates may represent any date in the proleptic Gregorian calendar.

import Time.Date as Date exposing (Date, date)

Constructing Dates

Use date to construct Date values. If given invalid values for the month and day, they are both clamped and the nearest valid date is returned.

> date 1992 2 28
Date { year = 1992, month = 2, day = 28 } : Date

> date 1992 2 31
Date { year = 1992, month = 2, day = 29 } : Date

> date 1992 2 128
Date { year = 1992, month = 2, day = 29 } : Date

Use year, month, and day to inspect Dates.

> d = date 1992 5 29
Date { year = 1992, month = 5, day = 29 } : Date

> Date.year d
1992 : Int

> Date.month d
5 : Int

> Date.day d
29 : Int

Manipulating Dates

setYear, setMonth and setDay can be used to create new Dates containing updated values for each respective field. Like date, these functions clamp their parameters and return the nearest valid date.

addDays can be used to add an exact number of days to a Date.

addYears and addMonths add a relative number of years and months to a date. If the target date is invalid, these functions continually subtract one day until a valid date is found.

import Time.Date as Date exposing (Date, date, addYears)
import Time.Iso8601

> date 1992 1 31
|   |> addYears 1
|   |> Time.Iso8601.fromDate
"1993-01-31" : String

> date 1992 2 29
|   |> addYears 1
|   |> Time.Iso8601.fromDate
"1993-02-28" : String

> date 1992 1 31
|   |> Date.addMonths 1
|   |> Time.Iso8601.fromDate
"1992-02-28" : String

DateTimes

DateTimes represent a Date together with the time information starting on midnight for the Date.

import Time.DateTime as DateTime exposing (DateTime, dateTime, year, month, day, hour, minute, second, millisecond)

Constructing DateTimes

DateTimes can be constructed from a record using the dateTime function or from a UTC timestamp in milliseconds using fromTimestamp. To construct a DateTime using dateTime, pass it a record containing fields for year, month, day, hour, minute, second and millisecond:

dt : DateTime
dt =
    dateTime { year = 1992, month = 5, day = 29, hour = 0, minute = 0, second = 0, millisecond = 0 }
    
year dt --> 1992
month dt --> 5
day dt --> 29
hour dt --> 0
minute dt --> 0
second --> 0
millisecond --> 0    

dt : DateTime
dt =
    dateTime { year = 1992, month = 2, day = 31, hour = 0, minute = 0, second = 0, millisecond = 0 }
    
year dt --> 1992
month dt --> 2
day dt --> 29 - Note clamped.
hour dt --> 0
minute dt --> 0
second --> 0
millisecond --> 0    

dt : DateTime
dt =
    dateTime { year = 1993, month = 2, day = 31, hour = 0, minute = 0, second = 0, millisecond = 0 }
    
year dt --> 1993
month dt --> 2
day dt --> 28 - Note clamped.
hour dt --> 0
minute dt --> 0
second --> 0
millisecond --> 0    

To make constructing DateTimes less tedious, the library provides Time.DateTime.zero:

> import Time.DateTime as DateTime exposing (DateTime, dateTime, zero)

> dateTime { zero | year = 1992 }
|   |> DateTime.toISO8601
"1992-01-01T00:00:00.000Z" : String

> dateTime { zero | year = 1992, month = 2, day = 28, hour = 5 }
|   |> DateTime.toISO8601
"1992-02-28T05:00:00.000Z" : String

Use fromTimestamp to construct a DateTime from a UTC timestamp in milliseconds:

> fromTimestamp 0
|   |> DateTime.toISO8601
"1970-01-01T00:00:00.000Z" : String

See examples/without-timezone for an example of how to construct DateTimes from local time.

Manipulating DateTimes

Like Time.Date, the DateTime module exposes functions for adding to and updating a DateTime's fields. The functions addYears and addMonths have the same behaviour as their Time.Date counterparts.

ZonedDateTimes

ZonedDateTimes represent a DateTime in a specific TimeZone. See examples/with-timezone for an example of how to use ZonedDateTimes.

import Time.TimeZones as TimeZones
import Time.ZonedDateTime as ZonedDateTime exposing (ZonedDateTime)