cletter

Locale-correct business correspondence, composed from focused units. No models, no I/O: same input always yields the same output.

cletter is the front door: it re-exports cgreet (salutations), cfarewell (valedictions) and cink (signature images), and adds what only makes sense together — locale resolution, openings, subjects, orthography, and advisories:

use cletter::{closing, opening, resolve_locale, salutation, subject};

assert_eq!(resolve_locale(Some("de"), Some("Zürich, Zug")), "de-CH");
assert_eq!(
    salutation("de-CH", "Frau Dr. Müller"),
    "Sehr geehrte Frau Dr. Müller",
);
assert_eq!(closing("de-CH", None), "Freundliche Grüsse");
assert_eq!(opening("en-US", Some("Jane Doe"), None), "Dear Jane Doe,");
assert_eq!(
    subject("de-CH", Some("Leiterin Kommunikation"), None),
    "Bewerbung als Leiterin Kommunikation",
);

One locale per document (BCP 47). Unknown locales fall back through the base language to English. Explicit overrides always win — user choice is never degraded, the tables only supply defaults.

Use

Rust:

[dependencies]
cletter = "0.1"

TypeScript (zero dependencies, runs in browsers, edge runtimes, and Node):

npm install @corbet-labs/cletter

Run cargo test, cargo fmt --check, and cargo clippy --all-targets -- -D warnings before pushing.

Contract for ports

Behavior is defined by data: tables/locales.json (openings, subjects, orthography, region mapping) and tables/countries.json (location to country resolution), documented in tables/README.md. tests/vectors/*.json is the executable conformance suite every language port runs. The Typst module in typst/ derives from the same tables. A port is done when every vector passes.

License

FSL-1.1-ALv2; see LICENSES/FSL-1.1-ALv2.txt. Each published version becomes available under Apache-2.0 two years after publication.