Fast, reliable, and secure dependency management.

Yarn is a modern package manager split into various packages. Its novel architecture allows to do things currently impossible with existing solutions:

• Yarn supports plugins; adding a plugin is as simple as adding it into your repository
• Yarn supports Node by default but isn't limited to it - plugins can add support for other languages
• Yarn supports workspaces natively, and its CLI takes advantage of that
• Yarn uses a portable shell to execute package scripts, guaranteeing they work the same way on Windows and Linux
• Yarn is first and foremost a Node API that can be used programmatically (via berry-core)
• Yarn is written in TypeScript, and fully typechecked

Because this repository is about the modern but experimental version of Yarn (aka Yarn v2), the install process is slightly different for the time being.

• Open one of your project
• First run yarn policies set-version nightly - to be sure that the next command will work
• Then run yarn policies set-version berry - this will fetch the v2 bundle
• And voilà! Just run any command, such as yarn config -v - they will use the v2
• To revert, just remove the local change to your .yarnrc file

The following packages are generic and can be used in a variety of purposes (including to implement other package managers, but not only):

• berry-core allows any application to manipulate a project programmatically.
• berry-json-proxy allows to temporarily convert any POD object to an immutable object.
• berry-libzip contains zlib+libzip bindings compiled to WebAssembly.
• berry-parsers can be used to parse Syml and the language used by berry-shell.
• berry-pnp can be used to generate Plug'n'Play-compatible hooks.
• berry-shell is a portable bash-like shell interpreter.
• berry-ui is a React renderer targeting terminals.
• berry-zipfs is a fs implementation that can read files from zip archives.

The following packages are plugins for Berry and can be installed through berry add plugin <plugin-name>. Note that some of them are typically already shipped with the regular Yarn bundles. Such plugins are marked with a star (★).

• plugin-constraints adds support for yarn constraints check and yarn constraints fix.
• plugin-essentials★ adds various commands deemed necessary for a package manager (add, remove, ...).
• plugin-file★ adds support for using file: references as dependencies.
• plugin-github★ adds support for using Github references as dependencies. This plugin doesn't use git.
• plugin-http★ adds support for using straight URL references as dependencies (tgz archives only).
• plugin-hub contains a UI designed to efficiently manage large-scale projects with multiple workspaces.
• plugin-init★ adds support for the yarn init command.
• plugin-link★ adds support for using link: and portal: references as dependencies.
• plugin-npm★ adds support for using semver ranges as dependencies, resolving them to an NPM-like registry.
• plugin-pnp★ adds support for installing Javascript dependencies through the Plug'n'Play specification.

To create your own plugin, please refer to the documentation.

The following packages are meant to be used by Yarn itself, and probably won't be useful to other applications:

• berry-builder contains a CLI tool to package berry and its plugins.
• berry-cli is a CLI entry point built on top of berry-core.

Clone this repository, then run the following commands:

$> yarn build:cli

Note that no other command is needed! Since our dependencies are checked-in within the repository (within the .yarn/cache directory), you don't need to run any install. Everything just works right after cloning the project, and is guaranteed to continue to work ten years from now 🙂