EDTFList

Represents "all members" of a list of dates (Level 2).

Interface

interface EDTFList extends EDTFBase {
  type: 'List';
  values: (EDTFDate | EDTFDateTime | EDTFSeason)[];
  earlier?: boolean;
  later?: boolean;
}

Properties

Property	Type	Description
type	'List'	Type discriminator
values	Array	Values in the list
earlier	boolean?	True if list includes earlier dates
later	boolean?	True if list includes later dates

Inherited from EDTFBase

Property	Type	Description
level	2	Always Level 2
edtf	string	Original EDTF string
precision	Precision	Based on list contents
min	Date	Earliest date
max	Date	Latest date

Usage

Lists are enclosed in curly braces {} and represent "all of these":

import { parse, isEDTFList } from '@edtf-ts/core';

const result = parse('{1667,1668,1670..1672}');

if (result.success && isEDTFList(result.value)) {
  const list = result.value;

  console.log(list.values.length);  // Number of values in list
  for (const value of list.values) {
    console.log(value.edtf);
  }
}

List Syntax

Simple List

A comma-separated list of dates:

parse('{1667,1668,1669}');
// All of: 1667, 1668, and 1669

List with Ranges

Use .. to specify ranges within a list:

parse('{1667,1668,1670..1672}');
// All of: 1667, 1668, 1670, 1671, and 1672

Earlier Values

Use .. at the start to include all earlier values:

parse('{..1760-12}');
// December 1760 and all earlier dates

const result = parse('{..1760-12}');
if (result.success && isEDTFList(result.value)) {
  console.log(result.value.earlier);  // true
}

Later Values

Use .. at the end to include all later values:

parse('{1760-12..}');
// December 1760 and all later dates

const result = parse('{1760-12..}');
if (result.success && isEDTFList(result.value)) {
  console.log(result.value.later);  // true
}

Examples

// Years
parse('{1667,1668,1669}');

// Months
parse('{2004-01,2004-02,2004-03}');

// Days
parse('{2004-06-01,2004-06-02,2004-06-03}');

// Mixed precision
parse('{1667,1668-12}');

// With ranges
parse('{1760..1765,1770}');

// Open-ended
parse('{..1760}');    // 1760 and earlier
parse('{1760..}');    // 1760 and later

Semantic Meaning

Lists express "all of" semantics:

const result = parse('{1667,1668,1669}');
// Meaning: The event occurred in ALL of 1667, 1668, and 1669
// (e.g., an annual event that happened each of those years)

This is different from Sets which express "one of" semantics.

Comparison with Sets

	Set []	List {}
Meaning	One of	All of
Example	[1667,1668]	{1667,1668}
Interpretation	Either 1667 or 1668	Both 1667 and 1668

Min/Max Bounds

The min and max properties span the entire list:

const result = parse('{1667,1668,1672}');
if (result.success) {
  console.log(result.value.min);  // 1667-01-01
  console.log(result.value.max);  // 1672-12-31
}

Type Guard

import { isEDTFList } from '@edtf-ts/core';

const result = parse(input);
if (result.success && isEDTFList(result.value)) {
  // TypeScript knows result.value is EDTFList
  console.log(result.value.values);
}

Related

• EDTFSet - "One of" semantics (square brackets)