A reusable Go module with no binary, for other Go code to import. A small documented API with sentinel and typed errors for errors.Is and errors.As, runnable examples, fuzzing, a consumer module that imports it from outside, and an apidiff check against the last release.
A Java library for other JVM code to depend on, built with Maven and make. A JPMS module exporting one package, JSpecify nullness checked by NullAway, Javadoc with doclint and examples that run as tests, generated-input property tests, a consumer project built against the installed jar, a japicmp API check and the sources and Javadoc jars Maven Central requires.
A typed Python library for PyPI in a src layout, built with uv and make. A py.typed marker, strict mypy, pytest with Hypothesis property tests on the newest and oldest supported Python, and a wheel and sdist checked with twine and installed in a clean environment.
A Rust library crate for crates.io with a small documented public API, a thiserror error enum, an optional serde feature, doctests on every public item, proptest property tests, rustdoc with warnings denied, and a cargo package check that compiles exactly what would be published.
A Rust library compiled to WebAssembly with wasm-bindgen and wasm-pack into an npm package with generated TypeScript types. Errors reach JavaScript as exceptions with stable codes; the logic is tested natively, the exports as wasm in Node with wasm-bindgen-test, and the packed tarball from a TypeScript consumer project.
A TypeScript package for npm, built to ESM with bundled type declarations by tsdown, checked by publint and Are the Types Wrong, tested with Vitest, and proven by installing the packed tarball into a clean consumer project.