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Add dxn_intl as a git dependency, learn how its pieces fit together, and format a first plural, price and date for a locale.

dxn_intl formats the three things apps localize most: plural forms, numbers and dates. You reach for it when text has to follow the user’s language (“1 file”, “2 files”, “5 datoteka”) and the same code has to print the same text in a native app, on a server and in WebAssembly.

#Install

The crate is not on crates.io. Releases are git tags (vX.Y.Z), so depend on a tag:

cargo add dxn_intl --git https://github.com/dXnSix/dXn.Intl --tag v0.1.0

or in Cargo.toml:

[dependencies]
dxn_intl = { git = "https://github.com/dXnSix/dXn.Intl", tag = "v0.1.1" }

Cargo.lock records the tagged commit. To upgrade, change the tag; see Releases. The crate has no Cargo features and needs Rust 1.97 or newer (the library is edition 2024, and CI checks 1.97).

The locale data is compiled into your binary, so there is nothing to download or ship next to it. There is no docs.rs page because the crate is not published; build the API reference with cargo doc --open.

#A first program

Every formatter is made from a Locale, which parse_locale reads from a language tag, plus the options for what it shows.

use dxn_intl::{
    DateTime, DateTimeFormatter, DateTimeOptions, IntlError, Length, NumberFormatter,
    NumberOptions, PluralKind, PluralRules, parse_locale,
};

fn main() -> Result<(), IntlError> {
    let locale = parse_locale("hr-HR")?;

    let plurals = PluralRules::new(&locale, PluralKind::Cardinal)?;
    println!("{}", plurals.category(23)); // few

    let money = NumberFormatter::new(&locale, NumberOptions::currency("EUR"))?;
    println!("{}", money.format(1234.5)?); // 1.234,50 €

    let dates = DateTimeFormatter::new(&locale, DateTimeOptions::date(Length::Long))?;
    println!("{}", dates.format(&DateTime::date(2026, 10, 27)?)?); // 27. listopada 2026.
    Ok(())
}

few
1.234,50 €
27. listopada 2026.

The snippets in these docs use ? and are meant to run inside a function that returns Result<_, IntlError> (or Result<_, Box<dyn std::error::Error>>: IntlError implements std::error::Error). Output shown in assert_eq! was produced by running the snippet.

#How the pieces fit

flowchart TB tag["language tag: en-US, pt_BR.UTF-8"] -->|parse_locale| locale[Locale] list["user's preferred list"] -->|negotiate| locale locale --> plurals[PluralRules] locale --> numbers[NumberFormatter] locale --> dates[DateTimeFormatter] value[Number] --> plurals value --> numbers wall[DateTime] --> dates

A formatter is built once for a locale and reused. Number and DateTime are plain values: a Number goes to the plural rules and the number formatter, a DateTime to the date formatter.

#What to reach for

You need	Use	Page
A locale from a tag, `LANG` or `Accept-Language`	`parse_locale`, `negotiate`	Locales
“1 item” or “2 items”	`PluralRules::category`	Plurals
“1st”, “2nd”, “3rd”	`PluralRules` with `PluralKind::Ordinal`	Plurals
`1,234.5`, `25%`, `$1,234.50`	`NumberFormatter` with `NumberOptions`	Numbers
The number as it will be shown	`NumberFormatter::resolve`	Numbers
`Oct 27, 2026`, `15:45`	`DateTimeFormatter` with `DateTimeOptions`	Dates and times
The wall time of a Unix timestamp	`DateTime::from_unix_millis`	Dates and times
Left to right or right to left	`direction`	Locales

#Things to know early

Formatters are not Send or Sync. PluralRules, NumberFormatter and DateTimeFormatter hold ICU4X data behind Rc, so they stay on the thread that made them. Number, DateTime, Locale and IntlError are Send + Sync. See Platforms.
Floats lose trailing zeros. 1.0_f64 becomes the number 1. Parse text ("1.0".parse::<Number>()) or format with fixed fraction digits when the digits matter. See Numbers.
No clock, no time zones. You pass the wall time. See Dates and times.
It is a 0.x library. A minor release can break the API; read the release notes before bumping.

#Next

Locales covers reading tags and choosing the locale to format for. Plurals is the page to read if you only need “1 item, 2 items”.