Introduction

Language tags are defined in BCP47. A friendly overview is available in the W3C article “Language tags in HTML and XML.” These tags are commonly used in HTML and in the Content-Language and Accept-Language HTTP headers.

Feature Highlights

• Typed coverage of BCP47 language tags through a single Language enum.
• Conversion helpers: tag, name, and local_name give tags, English names, and native names, with TryFrom for parsing.
• Language::all() provides a compile-time array for iterating over every language without allocation.
• Optional serde feature for serializing and deserializing language values.
• Code is generated directly from the translation.io “languages with plural cases” page; cargo build enforces validity and the language binary downloads fresh data when regenerating.
• Optional ICU4X interop (icu_locale_core feature) for converting to/from Locale and LanguageIdentifier.
• Optional whatlang interop (whatlang feature) for converting to/from whatlang::Lang with clear error reporting.
• Optional lingua interop (lingua feature) for converting to/from lingua::Language with clear error reporting.
• Optional SQLx interop (sqlx-postgres / sqlx-mysql / sqlx-sqlite) for Type/Encode/Decode support using textual tags.

Usage

// crates.io
use language::Language;

let en = Language::En;

assert_eq!(en.tag(), "en");
assert_eq!(Language::try_from("en").unwrap(), Language::En);
assert_eq!(en.name(), "English");
assert_eq!(en.local_name(), "English");

More examples

Parse user input safely (any invalid tag becomes a typed error):

// crates.io
use language::Language;

let parsed: Result<Language, _> = Language::try_from("zh-Hant");

assert!(parsed.is_ok());

let bad = Language::try_from("zz-INVALID");

assert!(bad.is_err());

Iterate over every language without allocation:

// crates.io
use language::Language;

let tags: Vec<&'static str> = Language::all().iter().map(Language::tag).collect();

assert!(tags.contains(&"fr-CA"));

serde (enable the serde feature):

// crates.io
use language::Language;
use serde::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize, PartialEq)]
struct Payload {
	lang: Language,
}

let json = r#"{"lang":"es-MX"}"#;
let payload: Payload = serde_json::from_str(json)?;

assert_eq!(payload.lang, Language::EsMx);

ICU4X interop (enable icu_locale_core):

// crates.io
use icu_locale_core::Locale;
use language::Language;

let locale: Locale = "pt-BR".parse()?;
let language = Language::try_from(&locale)?;

assert_eq!(language.tag(), "pt-BR");

whatlang interop (enable whatlang):

// crates.io
use language::Language;
use whatlang::Lang;

let lang = Language::try_from(Lang::Ukr)?;

assert_eq!(lang, Language::Uk);

lingua interop (enable lingua):

// crates.io
use language::Language;
use lingua::Language as LinguaLanguage;

let lang = Language::try_from(LinguaLanguage::Japanese)?;

assert_eq!(lang, Language::Ja);

SQLx (enable one of the sqlx-* features):

// crates.io
use language::Language;
use sqlx::types::Json;

// Language stores as a text tag; works with Postgres/MySQL/SQLite feature flags.
let stored = Language::Ja;
let row = sqlx::query!("select $1 as lang", stored)
	.fetch_one(&pool)
	.await?;

assert_eq!(row.lang, Language::Ja);

Support Me

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Your support is greatly appreciated and motivates me to keep improving this project.

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Thank you for your support!

Appreciation

We would like to extend our heartfelt gratitude to the following projects and contributors:

• The Rust community for their continuous support and development of the Rust ecosystem.
• translation.io for publishing the languages-with-plural-cases reference we build from.

Additional Acknowledgements

• Autonym data is downloaded from https://translation.io/docs/languages_with_plural_cases whenever you regenerate code with cargo run --features codegen --bin language.