cletter-0.2.1 has been yanked.

cletter

Locale-correct correspondence, from salutation to closing.

Compose a formal letter from deterministic rules: resolve a document locale, address a recipient, write an application subject, format the date, choose a closing, and prepare a handwritten signature image. Rust, JavaScript, and Python share the same conformance vectors.

import { salutation } from '@corbet-labs/cletter';

salutation('de-ch', 'Frau Dr. Müller');
// Sehr geehrte Frau Dr. Müller

Install

Environment	Command
Rust / Cargo	`cargo add cletter`
Node.js / npm	`npm install @corbet-labs/cletter`
pnpm	`pnpm add @corbet-labs/cletter`
Yarn	`yarn add @corbet-labs/cletter`
Bun	`bun add @corbet-labs/cletter`
Deno	`deno add npm:@corbet-labs/cletter`

The 0.2.1 JavaScript distribution includes compiled ESM, CommonJS, TypeScript declarations, and a standalone browser module. Node.js 20+ is supported; no TypeScript loader is required.

// CommonJS
const { salutation } = require('@corbet-labs/cletter');

<script type="module">
  import { salutation } from 'https://cdn.jsdelivr.net/npm/@corbet-labs/cletter@0.2.1/dist/browser.js';
  console.log(salutation('de-ch', 'Frau Dr. Müller'));
</script>

Python wheels, source distributions, and CLI instructions are in the installation guide. JSR publication and Typst availability are listed there explicitly.

Rust

use cletter::{closing, long_date, resolve_locale, salutation};

let locale = resolve_locale(Some("de"), Some("Zürich, Zug"));
assert_eq!(salutation(&locale, "Frau Dr. Müller"), "Sehr geehrte Frau Dr. Müller");
assert_eq!(closing(&locale, None), "Freundliche Grüsse");
assert_eq!(long_date(&locale, 2026, 9, 7).as_deref(), Some("7. September 2026"));

Python

from cletter import salutation

assert salutation("de-ch", "Frau Dr. Müller") == 'Sehr geehrte Frau Dr. Müller'

API

JavaScript / Python or Rust	Purpose
`resolveLocale` / `resolve_locale`	Language and location → document locale
`salutation`, `opening`	Recipient address or formal opening
`subject`	Application subject with optional prefix override
`closing`	Locale-specific valediction
`longDate` / `long_date` and other date helpers	Gregorian datelines
`applyOrtho` / `apply_ortho`	Explicit `ß` → `ss`, `ẞ` → `SS` for caller-selected `de-ch`/`de-li` prose
`orthographyIssues` / `orthography_issues`	Non-mutating matched source/replacement pairs
`orthographyReplacements` / `orthography_replacements`	Applicable spelling pairs from the shared table
`normalize`, `signatureSize` / `signature_size`	Signature-image preparation
`warnings`	Advisories for incomplete recipient details

Openings and closings have 40 locale entries. Date formatting currently covers German and English variants; other dates fall back to English. Locale IDs are lowercase in tables and outputs; lookups accept mixed case and explicit overrides win. Subject defaults are for job applications; supply a prefix override for other correspondence. The library produces letter components; your application owns the body, layout, and PDF rendering. Spelling transformations require caller-selected prose: preserve exact names, quotations, URLs and source material; use diagnostics when those boundaries are unavailable.

The self-contained Typst facade consumes the same greeting, closing and date helpers as the other ports.

Correspondence family

Library	Responsibility
cletter	Compose the correspondence helpers
cgreet	German salutations and titles
cfarewell	Locale-specific closings
cdate	Calendar-date formatting
cink	Handwritten signature images

Development

Behavior is defined by the locale tables and shared conformance vectors. Rust, JavaScript, and Python run the same vectors. Selected CI checks exercise installed JavaScript tarballs, Python wheels and command-line entrypoints, and Typst packages. Release validation records the actual runtime and platform; Linux results do not establish native Windows or macOS coverage. All five Rust crates forbid unsafe code in their own source.

See the release guide for generation, verification, and publication commands.

cletter 0.2.1