Datify-core is an API library that provides foundational localization data and patterns to format dates, powered directly by Unicode CLDR data (cldr-json) and designed for Typst. It is the backend for Datify, but is reusable in any Typst project needing localized month and day names or locale-specific date patterns.

If you need high-quality, up-to-date, and standards-based date strings for any supported language, whether for a date formatting tool, localization system, or any Typst workflow, datify-core is your solution.

Data quality: All locale data is sourced from cldr-json, which only includes CLDR data that has achieved draft="contributed" or draft="approved" status. This is the same threshold used by ICU (International Components for Unicode), ensuring high reliability and coverage.

Table of Contents

• Features
• Installation
• API Reference
  • get-day-name
  • get-month-name
  • get-date-pattern
• Supported Locales
• Community Overlay
• Testing
• Contributing
• License
• Credits

Features

• CLDR-sourced data: Day names, month names, and date patterns for hundreds of locales (languages and regional variants), generated directly from the Unicode CLDR.
• Simple API: Look up day/month names and date patterns by locale, usage, and width.
• Locale fallback: Unknown or region-specific codes resolve via the CLDR truncation chain (e.g. fr-CA → fr), ultimately falling back to the default locale (en), so a lookup never fails on an unrecognized locale.
• Reproducible & auto-updated: The data is pinned to an exact cldr-dates-full version and regenerated by a single tool; a scheduled job opens a PR when a newer CLDR release is available.
• Reusable: Designed for Datify, but works in any Typst project.

Installation

Install with Typst’s package manager or from preview:

#import "@preview/datify-core:2.1.0": *

(Replace version as needed.)

API Reference

get-day-name

Get the localized name of a weekday.

Parameters:

Example:

#get-day-name(1, lang: "fr", usage: "stand-alone", width: "wide") // lundi
#get-day-name(7, lang: "en", usage: "format", width: "abbreviated") // Sun

get-month-name

Get the localized name of a month.

Parameters:

Example:

#get-month-name(2, lang: "en", usage: "format", width: "abbreviated") // Feb
#get-month-name(8, lang: "de", usage: "stand-alone", width: "wide") // August

get-date-pattern

Get the date formatting pattern for a given locale.

Parameters:

Example:

#get-date-pattern("medium", lang: "de") // dd.MM.y

Supported Locales

datify-core ships CLDR data for 765 locales — day names, month names, and date patterns. Each locale stores only the values that are genuinely localized; any value a locale does not define is resolved through the CLDR fallback chain to its parent locale and ultimately to the default locale (en), so every supported locale returns sensible output. The full list is in src/translations/index.toml.

Community Overlay

CLDR is the single source of truth, but some locales have regional conventions or styling that CLDR doesn’t carry. Those live in an opt-in overlay under src/translations/community/, which is hand-maintained and never touched by the generator (so it survives the monthly regeneration).

Pass community: true to consult it. When enabled, a lookup tries the overlay first (resolved by the same truncation rule), and any cell the overlay doesn’t define falls through to CLDR. With community: false (the default), behavior is pure CLDR.

// CLDR (default)
#get-day-name(1, lang: "pt-BR", usage: "format", width: "narrow") // S
// With the overlay (Brazilian numbered narrow weekday)
#get-day-name(1, lang: "pt-BR", usage: "format", width: "narrow", community: true) // 2ª

The overlay holds only data that genuinely differs from CLDR (here, the narrow weekday representation). Casing is a presentation choice and is left to the caller — the overlay does not, for example, capitalize stand-alone names.

Overlay locales are keyed precisely (e.g. pt-BR, not pt) so they only affect the locales they target. To add or extend one, edit src/translations/community/locales/<locale>.toml (same section schema as the generated files, but partial) and list it in src/translations/community/index.toml.

Testing

To run the full test suite locally:

1. Manual (recommended for contributors) — install tt (tytanic), then:

   node tools/check-invariants.mjs   # structural checks over the data
   tt run                            # Typst tests
   

2. Via the GitHub Actions workflow locally with act:

   act --artifact-server-path /tmp/artifact
   

(Regenerating the data needs Node + npm ci; running the tests does not.)

Contributing

This package is intentionally opinionated: all locale data comes straight from the Unicode CLDR and is regenerated by tools/generate-cldr.mjs. The TOML files under src/translations/ are build artifacts — editing them by hand has no lasting effect, since the next regeneration overwrites them.

• Canonical locale fixes (wrong or missing translations) should go upstream to CLDR; corrections then flow in automatically on the next data update.
• Regional conventions or styling that CLDR doesn’t carry can go in the community overlay (src/translations/community/), which is hand-maintained and survives regeneration.
• Pull requests for bug fixes, the generator, or API enhancements are welcome.
• See cldr-json for the upstream data and structure.
• To run the tests, see the Testing section above.

License

MIT © 2026 Jeomhps CLDR data © Unicode, Inc., used under the Unicode License.

Credits

• Unicode CLDR Project
• cldr-json
• tytanic (Typst test runner)