Swim TypeScript Monorepo

This monorepo setup uses Yarn v3 Workspaces without Lerna. Lerna basically uses this Yarn functionality under the hood, adding higher-level features on top, but seems to be under-resourced as a project and has had some trouble meeting community demand. Since Yarn v2, the advantages of Lerna over built-in Yarn features are pretty minimal.

One of the major benefits of Yarn v2+ is its Plug'n'Play system for making dependency management more sane/efficient. In my experience the npm ecosystem is simply not ready for this as many packages do not conform to the strict standards required (eg specifying all dependencies correctly), but the promise is great. To begin with though, I’ve set the linker to node-modules (ie the classic approach we all know and hate).

Structure

Libraries live in packages and applications live in apps. As you can see in apps/example-ui/package.json, packages can reference each other via the workspace: prefix.

Publish to npm

This approach uses Lerna-style locked versioning, which simplifies a bunch of things at the cost of empty releases for some packages some of the time.

One-time setup

1. Login using yarn npm login --publish

For every release

1. Run yarn clean && git clean -xdf ./packages && yarn install && yarn build-packages
2. yarn workspaces foreach --no-private version <major|minor|patch>
3. If a file has been created under .yarn/versions which stores "undecided" package version info, delete it (this is not relevant to our fixed versioning approach).
4. Run git add . && git commit -m "chore: Bump version" && git tag v<version>
5. Either pre-release yarn publish-next or stable release yarn publish-latest
6. Run git push && git push --tags

To-do

• CLI example
• Consider Yarn’s Plug'n'Play - see these notes on migrating
• Do not remove tsconfig.tsbuildinfo every time we build, which reduces the effectiveness of incremental build (microsoft/TypeScript#30602)