glintl

Format dates and times in many languages, on Erlang and JavaScript.

import glintl
import glintl/locale/en_gb
import gleam/time/duration
import gleam/time/timestamp

let formatter =
  glintl.date_time_formatter(en_gb.locale(), date: glintl.Long, time: glintl.Short)

glintl.format(formatter, timestamp.system_time(), offset: duration.hours(1))
// -> "25 October 2026 at 23:40"

On Erlang the formats come from data baked into this package, made from ICU when the package is built. On JavaScript the runtime’s own Intl.DateTimeFormat is used, so the output can differ slightly between targets and between JavaScript runtimes.

Types

Formatter

opaque

Formats moments in time for one locale and style.

Make one and reuse it: making a formatter does the lookup work once, so formatting is cheap.

pub opaque type Formatter

Locale

opaque

A language and region to format for, such as British English.

Get one from a locale module, like glintl/locale/en_gb, or by tag from glintl/locales.

pub opaque type Locale

Style

How much detail to show, from most to least.

These are the same as the dateStyle and timeStyle options of JavaScript’s Intl.DateTimeFormat. In British English:

Style	Date	Time
`Full`	Sunday, 25 October 2026	23:40:58 GMT+01:00
`Long`	25 October 2026	23:40:58 GMT+1
`Medium`	25 Oct 2026	23:40:58
`Short`	25/10/2026	23:40

pub type Style {
  Full
  Long
  Medium
  Short
}

Constructors

```
Full
```
```
Long
```
```
Medium
```
```
Short
```

Values

date_formatter

pub fn date_formatter(
  locale: Locale,
  style style: Style,
) -> Formatter

Format only the date.

date_time_formatter

pub fn date_time_formatter(
  locale: Locale,
  date date: Style,
  time time: Style,
) -> Formatter

Format both the date and the time.

format

pub fn format(
  formatter: Formatter,
  timestamp: timestamp.Timestamp,
  offset offset: duration.Duration,
) -> String

Format a moment in time, as seen from a place offset ahead of UTC.

The offset is rounded down to whole minutes. Time zones are written as a GMT offset, like GMT+1, as glintl knows the offset but not the zone’s name.

locale_tag

pub fn locale_tag(locale: Locale) -> String

The BCP 47 tag of a locale, such as "en-GB".

time_formatter

pub fn time_formatter(
  locale: Locale,
  style style: Style,
) -> Formatter

Format only the time.