calcdate

Date Calculator

TL;DR

ES6

import { calc } from "calcdate";
// import { datefnscalc } from "calcdate"; // with date-fns
// import { luxoncalc } from "calcdate"; // with luxon
// import { luxonsimplecalc } from "calcdate"; // with luxon
// import { momentcalc } from "calcdate"; // with moment
// import moment from "moment";

const dval = calc();
// const dval = momentcalc(moment);

dval`now + 3 days + 5 hours`;

Node

const calc = require("calcdate").default;
// const luxoncalc = require("calcdate").luxoncalc;
// import luxon from "luxon";
const dval = calc();
// const dval = luxoncalc(luxon);

dval`now + 3 days + 5 hours`;

runkit api

https://embed-sw29njl68eg5.runkit.sh/P1d
// https://embed-sw29njl68eg5.runkit.sh/datefns/now+5d
// https://embed-sw29njl68eg5.runkit.sh/moment/now+5d
// https://embed-sw29njl68eg5.runkit.sh/luxon/now+5d

Install

yarn add calcdate

npm i calcdate

git repo

Find source code on git

Dependencies

There are no direct dependencies!

We recommend using this lib with your favourite date-time lib, use the bindings provided.

import	required dependency	import
datefnsCalculator	date-fns	import { datefnsCalculator } from "calcdate";
luxonCalculator	luxon	import { luxonCalculator } from "calcdate";
simpleluxonCalculator	luxon	import { simpleluxonCalculator } from "calcdate";
momentCalculator	moment	import { momentCalculator } from "calcdate";

Note You need to initialize the calculator with your library:

import { datefnsCalculator } from "calcdate"
import datefns from "datefns";

const calculator = datefnsCalculator(datefns);

Api docs

Calling the calculator is easy:

calculator`<expression>`

Example

// Imports
import { datefnsCalculator } from "calcdate"
import datefns from "datefns";
// Setup
const calculator = datefnsCalculator(datefns);

// Examples:
calculator`2009-12T12:34`;

calculator`P0002--10-15T10:+30:20`;

calculator`NOW + 7days`;

calculator`2009-12T12:00 - 2019-12T12:00`;

where calculator is your imported calculator and expression is what you want calculated. The following section outlines what is permitted in expressions.

Initializing

The calculator has to be initialized by passing it the library you are usigng it with with.

const luxon = require("luxon");
const calculator = require("calcdate").luxoncalc(luxon);

Types

Being a date-calculator the primary types used in expressions are date-times and the differences in between them (being durations and intervals).

Date-Time

A datetime is an exact point in time. It can be expressed as a ISO-8601-date-time (see w3 and wikipedia). Simply put, use the format YYYY-MM-DDThh:mm:ss.sss ("extended format"). All parts (but the year) are optional. If a part is not present, its default is used (0 for times and 1 for dates; 2019 = 2019-01-01T00:00:00.000). You can also use the normal form YYYYMMDD hhmmsssss. You can also add a time-zone using YYYY-MM-DDThh:mm:ss.sss+-hh:mm or YYYY-MM-DDThh:mm:ss.sssZ for utc.

Examples

2009-12T12:34 // Tue Dec 01 2009 12:34:00 GMT+1100 (Australian Eastern Daylight Time)
2009 // Thu Jan 01 2009 11:00:00 GMT+1100 (Australian Eastern Daylight Time)
2009-05-19 // Tue May 19 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
 2009-05-19  // Tue May 19 2009 00:00:00 GMT+1000 (Australian Eastern Standard Time)
2009-05 // Fri May 01 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
2009-001 // Thu Jan 01 2009 00:00:00 GMT+1100 (Australian Eastern Daylight Time)
2009-05-19 // Tue May 19 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T00:00 // Tue May 19 2009 00:00:00 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T14:31 // Tue May 19 2009 14:31:00 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T14:39:22 // Tue May 19 2009 14:39:22 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T14:39Z // Wed May 20 2009 00:39:00 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T14:39:22-06:00 // Wed May 20 2009 06:39:22 GMT+1000 (Australian Eastern Standard Time)
2009-05-19T14:39:22+0600 // Tue May 19 2009 18:39:22 GMT+1000 (Australian Eastern Standard Time)
2007-04-06T00:00 // Fri Apr 06 2007 00:00:00 GMT+1000 (Australian Eastern Standard Time)
200912T1234 // Tue Dec 01 2009 12:34:00 GMT+1100 (Australian Eastern Daylight Time)
2009 // Thu Jan 01 2009 11:00:00 GMT+1100 (Australian Eastern Daylight Time)
20090519 // Tue May 19 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
 20090519  // Tue May 19 2009 00:00:00 GMT+1000 (Australian Eastern Standard Time)
200905 // Fri May 01 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
2009001 // Thu Jan 01 2009 00:00:00 GMT+1100 (Australian Eastern Daylight Time)
20090519 // Tue May 19 2009 10:00:00 GMT+1000 (Australian Eastern Standard Time)
20090519 0000 // Tue May 19 2009 00:00:00 GMT+1000 (Australian Eastern Standard Time)
20090519 1431 // Tue May 19 2009 14:31:00 GMT+1000 (Australian Eastern Standard Time)
20090519 143922 // Tue May 19 2009 14:39:22 GMT+1000 (Australian Eastern Standard Time)
20090519 1439Z // Wed May 20 2009 00:39:00 GMT+1000 (Australian Eastern Standard Time)
20090519 143922-06:00 // Wed May 20 2009 06:39:22 GMT+1000 (Australian Eastern Standard Time)
20090519 143922+0600 // Tue May 19 2009 18:39:22 GMT+1000 (Australian Eastern Standard Time)
20070406 0000 // Fri Apr 06 2007 00:00:00 GMT+1000 (Australian Eastern Standard Time)

Binding depended

Each parser may provide its own parsing-from-string mechanism using {....}-notation.

Example {"2012 juillet", "YYYY MMM", "fr"} + moment-bindings {"12/11/2000", "MM/dd/yyyy"} + luxon-bindings

Duration

A duration expresses a time-period, aka "how long". A duration may be expressed using an iso-duration or the short-hand notation as follows.

Note Without a start- or end-date (see Interval) the units in a duration are hard to compare. For example, a duration of 1 month can be either anywhere from 28 days (2019-02-01/2019-03-01) to 31 days (2019-12-01/2020-01-01). Therefore some operations might be unsafe to perform, such as 1 month / 1 days (interpreted as "how many days fit into a month"). Depending on the bindings a loss of information and accuracy may occurs. (Also see luxon-notes.)

Short-hand notation

Each short-hand notation has three different forms which can be used synonymously: spelled-out singular, plural and shorthand (which makes it a shorthand-shorthand, I guess?). Whitespace is irrelevant. So 1 day, 1 days, 1 d, 1day, 1days, 1d all mean "1 day".

singular	plural	shorthand	example	notes
millisecond	milliseconds	ms	5ms
second	seconds	s	1 s	alias: ss, sec
minute	minutes	m	1 min	alias: min, mm, Tm
hour	hours	h	1 h	alias: hh
day	days	d	1 d
weekday	weekdays	wd	1 wd
week	weeks	w	1 w
fortnight	fortnights	fn	1 fn	= two weeks
month	months	M	1 M	alias: l, L
quarter	quarters	q	1 q
year	years	y	1 y	alias: a

In general these notation are caseinsensetive and can be pluralized, with the following exceptions:

• M, months, not to be confused with m, minutes
• m, minutes, see above
• ms, milliseconds, not to be confused Ms, plural of M, months

Iso-Notation

Durations may be written in iso as PnYnMnDTnHnMnS (where n is a any number). From wikipedia:

P is the duration designator (for period) placed at the start of the duration representation.

Y is the year designator that follows the value for the number of years.

M is the month designator that follows the value for the number of months.

W is the week designator that follows the value for the number of weeks.

D is the day designator that follows the value for the number of days.

T is the time designator that precedes the time components of the representation.

H is the hour designator that follows the value for the number of hours.

M is the minute designator that follows the value for the number of minutes.

S is the second designator that follows the value for the number of seconds.

"+" and "-" are allowed for the entire expression and parts individually. Thus +P1Y (1 year), -P1Y (minus 1 year) and -P-1y (minus minus 1 year = 1 year) are valid.

Examples

// Iso extended form, any number of digits allowed
P1Y2M3DT4H05M600S // 1 year, 2 months, 3 days, 4 hours, 5 minutes, 600 seconds
PT3H5M // 3 hours, 5 minus
P1Y // 1 year
P-1Y1M // -1 year, 1 month -> effectively 11 month
P1DT-30S // 1 day, -30 seconds
P1Y // 1 year
P2M // 2 month
P3D // 3 days
PT4H // 4 hours
PT05M // 5 minutes; padding with 0s is allowed
PT600S // 600 seconds; more than 2 digits are allowed
P1y2m3dT4h5m6s // 1 year, 2 months, 3 days, 4 hours, 5 minutes, 6 seconds; case-insensitive
// Iso-short-form, 4 digits for year, 2 for each other component
P00021015T103020 // 2 years, 10 months, 15 days, 10 hours, 30 minutes, 20 seconds
P00021015 // 2 years, 10 months, 15 days
P0002-10-15T10:30:20 // 2 years, 10 months, 15 days, 10 hours, 30 minutes, 20 seconds
P0002-10-15 // 2 years, 10 months, 15 days
+P00021015T103020
+P00021015
+P0002-10-15T10:30:20
+P0002-10-15
-P00021015T103020 // -2 years, -10 months, -15 days, -10 hours, -30 minutes, -20 seconds
-P00021015
-P0002-10-15T10:30:20
-P0002-10-15
P+00021015T103020
P0002-1015
P0002--10-15T10:+30:20 // 2 years, -10 month, 15 days, 10 hours, 30 minutes, 20 seconds
P0002-10--15 // 2 years, 10 months, -15 days
-P0002-10--15 // -2 years, -10 months, --15 days = 15 days

Note The time designator is mandatory when denoting times, so P1H would be invalid while PT1H would be fine.

Binding depended

Each parser may provide its own parsing-from-string mechanism using [....]-notation.

Example [ {"years": 1, "quarters"": 3, "milliseconds": 27} ] + luxon-bindings - uses luxon.Duration.fromObject

Interval

An interval expresses the duration between a start- and an end-date. It can be understood as a box for two dates and the duration in between. Hence an interval can be constructed by providing a start- and an end-date, or a start-date and a duration (end-date = start-date + duration), or an end-date and a duration (start-date = end-date - duration).

Intervals may be written as Iso-intervals. The three options are:

• Iso-Date-Time/Iso-Date-Time
• Iso-Date-Time/Iso-Duration
• Iso-Duration/Iso-Date-Time

Iso-Date-Time and Iso-Duration use the same parsing mechanisms described above and hence allow the notations outlined above.

Examples

2009-12T12:34/20090519 143922+0600
P1Y2M3DT4H05M600S/2009-12T12:34
2009-12T12:34/P1Y2M3DT4H05M600S

For more examples, combine any date-time example with another date-time-example or any duration-example.

Note Not all bindings support intervals!

Binding depended

Each parser may provide its own parsing-from-string mechanism using ~....~-notation.

Example ~2007-03-01T13:00:00Z/P1Y2M10DT2H30M~ + luxon-bindings - uses luxon.Interval.fromISO

Unitless

You may enter "bare" numbers, such as 2. They are treated as such. This might be useful for scalar operations such as 2 * 2d (= 4 d).

Examples

1
0
100
-10
-5
0
-09
1 + 1 // 2
10 + 15 - 25 // 0
3 * 5 // 15
3d * -1 // -3d
88 / 11 // 8
1 / 2 // 0.5
2.5 * 2 // 5
2d * 5 // 10d
7 - 8 // -1

Warning

Longer number are going to be interpreted as Iso-dates and thus might fail parsing! If you need to use numbers with more digits than 3, consider using interpolation instead.

2000 // 2000-01-01T00:00:00
`${2000}` // 'number' 2000

Custom / Existing values

Use interpolation to insert custom type:

calculator`${any_thing_here}`

This allows you to use your existing Date/luxon-Date-Times/moments/luxon-Intervals/... directly in the calculator.

The bindings define what custom types are supported!

That means, if you interpolate a datefnsCalculator with a luxon-Date-Time it will likely throw an error, as date-fns can't make sense of the luxon-object.

Examples

import DateTime from 'luxon/src/datetime.js';

luxonCalculator`${DateTime.fromSQL(...)} + ${{ hours: 3, minutes: 13 }}`

import moment from 'moment';

momentCalculator`${moment()} + ${moment.duration(2, 'seconds');}`

Operations

Add ("plus", "+")

Adds two "things". The binding implementation defines what "add" means and if it has a meaning at all!

Example 1d + 1h

Binding	Type a	Type b	Result	Notes
simple	Date	Date	Error
simple	Date	Duration	Timestamp (Int)	Loses accuracy due to conversion
simple	Duration	Date	Timestamp (Int)	Loses accuracy due to conversion
simple	Duration	Duration	Duration
simple	Unitless	Unitless	Unitless
simple	Unitless	*	Error
simple	any	any	any	Cast to date/duration; else error
-------	--------	--------	---------------	--------------------------------
date-fns	Date	Date	Error
date-fns	Date	Duration	Date
date-fns	Duration	Date	Date
date-fns	Duration	Duration	Duration
date-fns	Unitless	Unitless	Unitless
date-fns	*	*	Error
-------	--------	--------	---------------	--------------------------------
luxon	Date	Date	Error
luxon	Date	Duration	Date
luxon	Date	Interval	Date	Date + Duration(Interval)
luxon	Duration	Date	Date
luxon	Duration	Duration	Duration
luxon	Duration	Interval	Interval	Shifts interval by duration
luxon	Interval	Date	Interval	Interval extended to Date
luxon	Interval	Duration	Interval	Shifts interval by duration
luxon	Interval	Interval	Interval	Union of intervals
luxon	Unitless	Unitless	Unitless
luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
simple-luxon	Date	Date	Error
simple-luxon	Date	Duration	Date
simple-luxon	Duration	Date	Date
simple-luxon	Duration	Duration	Duration
simple-luxon	Unitless	Unitless	Unitless
simple-luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
moment	Date	Date	Error
moment	Date	Duration	Date
moment	Duration	Date	Date
moment	Duration	Duration	Duration
moment	Unitless	Unitless	Unitless
moment	*	*	Error

Subtract ("minus", "-")

Subtracts two "things" - binding defines the meaning. Can also be interpreted as a "until", as in "2019 - 2020" yielding an interval between those in some implementations.

Example 1d - 5h

Binding	Type a	Type b	Result	Notes
simple	Date	Date	Number	Difference of times in milliseconds
simple	Date	Duration	Timestamp (Int)	Loses accuracy due to conversion
simple	Duration	Date	Timestamp (Int)	Same as Date - Duration
simple	Duration	Duration	Duration
simple	Unitless	Unitless	Unitless
simple	*	*	*	Cast to date/duration; else error
-------	--------	--------	---------------	--------------------------------
date-fns	Date	Date	Duration	Difference between the two dates
date-fns	Date	Duration	Date
date-fns	Duration	Date	Date	Same as Date - Duration
date-fns	Duration	Duration	Duration
date-fns	Unitless	Unitless	Unitless
date-fns	*	*	Error
-------	--------	--------	---------------	--------------------------------
luxon	Date	Date	Interval	Interval(start: Date a, end: Date b)
luxon	Date	Duration	Date	Puts date into the past by duration
luxon	Date	Interval	Date	Date - Duration(Interval)
luxon	Duration	Date	Date	Same as Date - Duration
luxon	Duration	Duration	Duration
luxon	Duration	Interval	Interval	Same as Interval - Duration
luxon	Interval	Date	Interval	Limits Interval by Date
luxon	Interval	Duration	Interval	Shifts interval by duration
luxon	Interval	Interval	Interval	Intersection or Interval between both
luxon	Unitless	Unitless	Unitless
luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
simple-luxon	Date	Date	Error
simple-luxon	Date	Duration	Date
simple-luxon	Duration	Date	Error
simple-luxon	Duration	Duration	Duration
simple-luxon	Unitless	Unitless	Unitless
simple-luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
moment	Date	Date	Error
moment	Date	Duration	Date
moment	Duration	Date	Error
moment	Duration	Duration	Duration
moment	Unitless	Unitless	Unitless
moment	*	*	Error

Multiply ("*")

Example 5d * 3

Binding	Type a	Type b	Result	Notes
simple	Duration	Unitless	Duration
simple	Unitless	Duration	Duration
simple	Unitless	Unitless	Unitless
simple	*	*	Error
-------	--------	--------	---------------	--------------------------------
date-fns	Duration	Unitless	Duration
date-fns	Unitless	Duration	Duration
date-fns	Unitless	Unitless	Unitless
date-fns	*	*	Error
-------	--------	--------	---------------	--------------------------------
luxon	Unitless	Interval	Interval	Shifts Interval.start back
luxon	Interval	Unitless	Interval	Shifts Interval.start forward
luxon	Duration	Unitless	Duration
luxon	Unitless	Duration	Duration
luxon	Unitless	Unitless	Unitless
luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
simple-luxon	Duration	Unitless	Duration
simple-luxon	Unitless	Duration	Duration
simple-luxon	Unitless	Unitless	Unitless
simple-luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
moment	Duration	Unitless	Duration
moment	Unitless	Duration	Duration
moment	Unitless	Unitless	Unitless
moment	*	*	Error

Divide ("/")

Divide things Split "things" into n equal parts.

Binding	Type a	Type b	Result	Notes
simple	Duration	Unitless	Duration
simple	Unitless	Unitless	Unitless
simple	*	*	Error
-------	--------	--------	---------------	--------------------------------
date-fns	Duration	Unitless	Duration
date-fns	Unitless	Duration	Duration	Inverts each duration part
date-fns	Duration	Duration	Unitless	Loses accuracy due to conversion
date-fns	Unitless	Unitless	Unitless
date-fns	*	*	Error
-------	--------	--------	---------------	--------------------------------
luxon	Date	Date	Interval	Interval(start: Date a, end: Date b)
luxon	Interval	Unitless	Duration	Duration c fits Unitless times into Interval
luxon	Interval	Duration	Unitless	Duration b fits Unitless times into Interval
luxon	Interval	Unitless	Duration
luxon	Duration	Duration	Unitless	Loses accuracy due to conversion
luxon	Duration	Unitless	Duration
luxon	Unitless	Duration	Duration	Inverts each duration part
luxon	Interval	1u	Interval	Swops the interval (start->end, end->start)
luxon	Unitless	Unitless	Unitless
luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
simple-luxon	Duration	Unitless	Duration
simple-luxon	Unitless	Unitless	Unitless
simple-luxon	*	*	Error
-------	--------	--------	---------------	--------------------------------
moment	Duration	Unitless	Duration
moment	Unitless	Unitless	Unitless
moment	*	*	Error

Other

Additionally ( + ) is permitted to group any expression and give its evaluation priority. Nesting is allowed. (Or expressed differently: (...) works as you would expect!)

Example ( 1d - 5h ) * 2

On top there is the keywords "now" (alias "today", both case-insensitive), which creates a Date-Time with the value of "now".

Operator precedence

Priority	Expression	Example
1	Interval	2009-12T12:34/20090519 143922+0600
2	now, today	now, now(), Today
2	Custom Constructor	{....}, [....], ~....~
2	Duration	P1D
2	Date-Time	2019
2	Duration shorthand	1 day
3	Unitless	1
4	Brackets	( .... )
5	Multiply	.. * ..
5	Divide	.. / ..
6	Plus	.. + ..
6	Minus	.. - ..

This order insures that 2019/P1D is an interval while 2019 / P1D means "divide 2019 by P1D". It also care to interpret 2019-08 as "August of 2019", while 2019 - 08 means "The date 2019 minus unitless 8".

Bring your own lib date-lib

The date-calculator itself is not bound to any library. You can 'teach' it to work with any library by implementing 'bindings'. To create a new calculator type import the calculatorFactory (aka "parser") and call it with your bindings (see below).

import calculatorFactory from "./calcdate";

const yourCalculator = calculatorFactory({
    makeDate: ...,
    makeDuration: ...,
    makeInterval: ...,
    add: ...,
    subtract: ...,
    multiply: ...,
    divide: ...
});

You will need to implement the following methods:

makeDate

You function to create a new date. It can take the following two signatures:

• makeDate(date: Native_Date, { type: calculatorFactory.NATIVEDATE }) : YourDateType
• makeDate(date: any, { type: calculatorFactory.DATEXPRESION }) : YourDateType, created by calculator{any_string}

makeDuration

• makeDuration({ milliseconds, seconds, minutes, hours, days, weekdays, weeks, months, years } : { milliseoncds: Number?, seconds: Number?, minutes: Number?, hours: Number?, days: Number?, weekdays: Number?, weeks: Number?, months: Number?, years: Number? }, { type: calculatorFactory.DURATIONOBJECT }) : YourDurationType
• makeDuration(duration: any, { type: calculatorFactory.DURATIONEXPRESSION }) : YourDurationType, created by calculator[any_string]

makeInterval

• makeInterval([from: YourDateType, to: YourDateType], { type: calculatorFactory.INTERVALOBJECT }) : YourIntervalType
• makeInterval([from: YourDateType, to: YourDurationType], { type: calculatorFactory.INTERVALOBJECT }) : YourIntervalType
• makeInterval([from: YourDurationType, to: YourDateType], { type: calculatorFactory.INTERVALOBJECT }) : YourIntervalType
• makeInterval(interval: any, { type: calculatorFactory.DURATIONEXPRESSION }) : INTERVALEXPRESION, created by calculator~any_string~

add

add(a, b) : c, where a, b, c are YourDateType | YourDurationType | YourIntervalType | { unitless: Number } | any

Examples

• now + 1 day - add(a: YourDateType, b: YourDurationType)
• now + 1 - add(a: YourDateType, { unitless: 1 } : { unitless: Number })
• P3Y6M4DT12H30M5S + 1 day - add(a: YourDurationType, b: YourDurationType)
• 2019-01-01/2019-01-02 + now - add(a: YourIntervalType, b: YourDateType)
• ${new RegExp("foobar")} + ~hello world~ - add(a: any, b: YourIntervalType)
• 1d + 1h + 1m - add(add(a: YourDurationType, b: YourDurationType), x: YourDurationType)

Note You should throw (helpful) errors when you can't make sense of the arguments. For example adding up two duration makes sense - adding up two dates might not! The same applies for all the operations!

subtract

subtract(a, b) : c, where a, b, c are YourDateType | YourDurationType | YourIntervalType | { unitless: Number } | any

• now - 1 day - subtract(a: YourDateType, b: YourDurationType)
• now - 1 - subtract(a: YourDateType, { unitless: 1 } : { unitless: Number })
• P3Y6M4DT12H30M5S - 1 day - subtract(a: YourDurationType, b: YourDurationType)
• 2019-01-01/2019-01-02 - now - subtract(a: YourIntervalType, b: YourDateType)
• ${new RegExp("foobar")} - ~hello world~ - subtract(a: any, b: YourIntervalType)
• 1d - 1h - 1m - subtract(add(a: YourDurationType, b: YourDurationType), x: YourDurationType)

Note You should throw (helpful) errors when you can't make sense of the arguments. For example substracting a duration from a date makes sense - substracting a date from a duration might not!

multiply

multiply(a, b) : c, where a, b, c are YourDateType | YourDurationType | YourIntervalType | { unitless: Number } | any

• now * 1 day - multiply(a: YourDateType, b: YourDurationType)
• now * 1 - multiply(a: YourDateType, { unitless: 1 } : { unitless: Number })
• P3Y6M4DT12H30M5S * 1 day - multiply(a: YourDurationType, b: YourDurationType)
• 2019-01-01/2019-01-02 * now - multiply(a: YourIntervalType, b: YourDateType)
• ${new RegExp("foobar")} * ~hello world~ - multiply(a: any, b: YourIntervalType)
• 1d * 1h * 1m - multiply(add(a: YourDurationType, b: YourDurationType), x: YourDurationType)

Note You should throw (helpful) errors when you can't make sense of the arguments. For example multiplying a duration by a unitless makes sense - multiplying a duration by another might not!

divide

divide(a, b) : c, where a, b, c are YourDateType | YourDurationType | YourIntervalType | { unitless: Number } | any

• now / 1 day - divide(a: YourDateType, b: YourDurationType)
• now / 1 - divide(a: YourDateType, { unitless: 1 } : { unitless: Number })
• P3Y6M4DT12H30M5S / 1 day - divide(a: YourDurationType, b: YourDurationType)
• 2019-01-01/2019-01-02 / now - divide(a: YourIntervalType, b: YourDateType)
• ${new RegExp("foobar")} / ~hello world~ - divide(a: any, b: YourIntervalType)
• 1d / 1h / 1m - divide(add(a: YourDurationType, b: YourDurationType), x: YourDurationType)

Note You should throw (helpful) errors when you can't make sense of the arguments. For example dividing a duration by another might make sense (could be "how many durations x fit into duration y") - dividing a unitless by an interval might not!