Localize Playground

Locale & calendar

Locale Calendar Try :japanese, :hebrew, :islamic, :buddhist, :ethiopic… Style / width Context Affects capitalisation + choice of variant.

Calendar system

The localized display name of the calendar system itself — derived from CLDR via Localize.Calendar.display_name/3.

Gregorian Calendar

Localize.Calendar.display_name(:calendar, :gregorian, locale: "en")

Months

Month numbers are 1-based. Some calendars (e.g. Hebrew) have 13 months.

Month	Value	Localized name
1	`1`	January
2	`2`	February
3	`3`	March
4	`4`	April
5	`5`	May
6	`6`	June
7	`7`	July
8	`8`	August
9	`9`	September
10	`10`	October
11	`11`	November
12	`12`	December

Days of week

ISO 8601 day numbers: 1 = Monday through 7 = Sunday. The first day varies by locale — see the Week info panel below.

Day	Value	Localized name
1	`1`	Monday
2	`2`	Tuesday
3	`3`	Wednesday
4	`4`	Thursday
5	`5`	Friday
6	`6`	Saturday
7	`7`	Sunday

Quarters

Quarter	Value	Localized name
1	`1`	1st quarter
2	`2`	2nd quarter
3	`3`	3rd quarter
4	`4`	4th quarter

Eras

Each calendar defines its own era sequence. E.g., :japanese has Meiji, Taisho, Shōwa, Heisei, Reiwa; :gregorian has BC / AD.

Era	Value	Localized name
0	`0`	Before Christ
1	`1`	Anno Domini

Day periods

AM/PM plus CLDR's flexible day-period set: :morning1, :afternoon1, :evening1, :night1, etc. Not every locale defines every period.

Period	Value	Localized name
am	`:am`	AM
pm	`:pm`	PM
noon	`:noon`	noon
midnight	`:midnight`	midnight
morning1	`:morning1`	in the morning
afternoon1	`:afternoon1`	in the afternoon
evening1	`:evening1`	in the evening
night1	`:night1`	at night

Date-time field names

Localized labels for the individual fields — useful for form captions, error messages, and chrono-aware UIs.

Field	Value	Localized name
era	`:era`	era
year	`:year`	year
quarter	`:quarter`	quarter
month	`:month`	month
week	`:week`	week
weekday	`:weekday`	day of the week
day	`:day`	day
day_period	`:day_period`	AM/PM
hour	`:hour`	hour
minute	`:minute`	minute
second	`:second`	second
zone	`:zone`	time zone

Year

Pattern	Meaning	Example
`y`	Calendar year. Truncates to min digits.	`2026 · 26`
`yy`	2-digit year.	`26`
`yyyy`	4-digit year (zero-padded).	`2026`
`Y`	Week-based year (ISO).	`2026`
`u`	Extended year.	`2026`
`U`	Cyclic year name (e.g., Chinese zodiac).	`丙午`
`r`	Related Gregorian year.	`2026`

Time zone — specific

Pattern	Meaning	Example
`z`	Short specific non-location.	`PT`
`zzzz`	Long specific non-location.	`Pacific Time`
`Z`	ISO 8601 basic (-0800).	`-0800`
`ZZZZ`	Long localized GMT.	`GMT-08:00`
`ZZZZZ`	ISO 8601 extended (-08:00) or 'Z'.	`-08:00`
`O`	Short localized GMT.	`GMT-8`
`OOOO`	Long localized GMT.	`GMT-08:00`

Time zone — generic & location

Pattern	Meaning	Example
`v`	Short generic non-location.	`PT`
`vvvv`	Long generic non-location.	`Pacific Time`
`V`	Short time zone ID.	`uslax`
`VV`	Long time zone ID.	`America/Los_Angeles`
`VVV`	Exemplar city.	`Los Angeles`
`VVVV`	Generic location format.	`Los Angeles Time`
`X`	ISO 8601 with Z for UTC (-08, -0800, Z).	`-08`
`x`	ISO 8601 numeric (-0800, no Z).	`-0800`

Simple vs complex messages

Syntax	Meaning	Example output
`Hello, world!`	Simple message — plain text is a valid message.	`Hello, world!`
`{{Hello, {$name}!}}`	Quoted pattern — required when the message has declarations, matchers, or starts with { or .	`Hello, Aoife!`
`.local $x = {1} {{Value: {$x}}}`	Complex message — declarations followed by a quoted pattern.	`Value: 1`

Placeholders

Syntax	Meaning	Example output
`{$name}`	Variable reference — binds to the bindings map/keyword.	`Aoife`
`{\|literal text\|}`	Literal — explicit quoted value. Rare in practice.	`literal text`
`{42}`	Number literal.	`42`
`{$x :number}`	Annotated variable — applies a function to the value.	`3`
`{$x :number minimumFractionDigits=2}`	Annotated with options.	`3.00`

Built-in functions

Syntax	Meaning	Example output
`:string`	Selects/formats a string value (default for strings).
`:number`	Formats a number. Options: minimumFractionDigits, maximumFractionDigits, minimumIntegerDigits, useGrouping, signDisplay, notation.	`1,234.50`
`:integer`	Formats an integer.	`1,234`
`:currency`	Formats as currency. Options: currency=ISO, currencyDisplay=code\|symbol\|name\|narrowSymbol.	`$1,234.56`
`:date`	Formats a date. Options: dateStyle=short\|medium\|long\|full.	`Apr 15, 2026`
`:time`	Formats a time. Options: timeStyle=short\|medium\|long\|full.	`3:04 PM`
`:datetime`	Formats a date and time.	`Apr 15, 2026, 3:04 PM`

Selection / matchers

Syntax	Meaning	Example output
`.match $count`	Select a variant based on one or more selectors.
`0 {{No items.}}`	Literal variant — matched when $count == 0.	`No items.`
`one {{1 item}}`	Plural keyword variant (:number selector).	`1 item`
`* {{N items.}}`	Default/wildcard variant. Required.	`N items.`
`.match $a $b hi hi {{both hi}} * * {{anything}}`	Multi-selector — one row per combination. Wildcards * act as catch-alls.

Common patterns

Syntax	Meaning	Example output
`.match {$count :number} one {{1 unread}} * {{{$count} unread}}`	Plural message using CLDR plural categories.	`3 unread`
`.match {$gender :string} feminine {{She}} masculine {{He}} * {{They}}`	Gender/string selection.	`They`
`{{Total: {$amount :currency currency=USD}}}`	Currency formatting with options.	`Total: $1,234.56`
`{{Today is {$d :date dateStyle=full}}}`	Long date.	`Today is Wednesday, April 15, 2026`

Pattern	Meaning	Example
`Q`	Quarter number.	`2`
`QQ`	Quarter number, 2-digit.	`02`
`QQQ`	Abbreviated quarter name.	`Q2`
`QQQQ`	Wide quarter name.	`2nd quarter`
`q`	Stand-alone quarter (same but in isolation).	`2`

Pattern	Meaning	Example
`M`	Month number.	`4`
`MM`	Month number, 2-digit.	`04`
`MMM`	Abbreviated month name.	`Apr`
`MMMM`	Wide month name.	`April`
`MMMMM`	Narrow month name.	`A`
`L`	Stand-alone month number.	`4`
`LLLL`	Stand-alone wide month name.	`April`

Pattern	Meaning	Example
`w`	Week of year.	`15`
`ww`	Week of year, 2-digit.	`15`
`W`	Week of month.	`3`

Pattern	Meaning	Example
`d`	Day of month.	`15`
`dd`	Day of month, 2-digit.	`15`
`D`	Day of year.	`105`
`F`	Day of week in month (e.g., 3rd Tuesday).	`3`
`g`	Modified Julian Day.	`2460785`

Pattern	Meaning	Example
`E`	Abbreviated day name.	`Wed`
`EEEE`	Wide day name.	`Wednesday`
`EEEEE`	Narrow day name.	`W`
`e`	Local day of week (locale-dependent start).	`4`
`c`	Stand-alone day of week.	`4`
`cccc`	Stand-alone wide day name.	`Wednesday`

Pattern	Meaning	Example
`a`	AM/PM marker.	`PM`
`aaaa`	Wide AM/PM marker.	`in the afternoon`
`b`	AM/PM + noon/midnight.	`noon`
`B`	Flexible day period.	`in the afternoon`

Pattern	Meaning	Example
`h`	Hour 1–12.	`6`
`hh`	Hour 1–12, 2-digit.	`06`
`H`	Hour 0–23.	`18`
`HH`	Hour 0–23, 2-digit.	`18`
`K`	Hour 0–11.	`6`
`k`	Hour 1–24.	`18`
`j`	Locale's preferred hour field (use in skeletons).	`6 PM`
`J`	Locale's preferred hour without day period.	`18`

Pattern	Meaning	Example
`m`	Minute.	`9`
`mm`	Minute, 2-digit.	`09`
`s`	Second.	`7`
`ss`	Second, 2-digit.	`07`
`S`	Fractional second.	`1`
`SSS`	Milliseconds.	`123`
`A`	Milliseconds of day.	`65430000`

Pattern	Meaning	Example
`G`	Era abbreviation.	`AD`
`GGGG`	Era wide.	`Anno Domini`
`GGGGG`	Era narrow.	`A`

Pattern	Meaning	Example
`'text'`	Literal text inside single quotes.	`'at' → at`
`''`	Escaped single quote.	`it's → it''s`
`:`	Time separator placeholder (locale-adjusted).	`:`

Syntax	Meaning	Example output
`.local $x = {expr}`	Bind a local variable to an expression (placeholder).
`.input {$x :number}`	Re-annotate an incoming binding with a function/options.

Syntax	Meaning	Example output
`{#link}Click here{/link}`	Open / close markup — the formatter can emit structured output (HTML, etc.).
`{#img src=\|photo.jpg\| /}`	Self-closing markup with options.

Syntax	Meaning	Example output
`\{`	Literal open brace.	`{`
`\}`	Literal close brace.	`}`
`\\`	Literal backslash.	`\`
`\\|`	Literal pipe inside \|...\| literals.	`\|`