Infer project references from common monorepo patterns / tools

Genesis: see section “Repetitive configuration” in https://github.com/Microsoft/TypeScript/issues/3469#issuecomment-400439520

Search Terms

monorepo infer project references automatically yarn lerna workspace package.json

Suggestion

For common monorepo managers, we should natively understand cross-project references declared in package.json as if they were declared in tsconfig.json

Open questions:

• Which formats (lerna, yarn, pnpm, etc) would be supported? Can all of them be consistently detected, or would you need to opt in to a specific “monorepo format” to enable a specific resolution algorithm?
• How do we find the tsconfig.json file? This data is actually not present in the current (non-tsconfig) dependency graph. We could assume it to be in the package root; what if it’s elsewhere?
• Would you need to opt in? Would there be a way to opt out? What should that look like?

Use Cases

• Monorepos of all (supportable) flavors

Examples

https://github.com/RyanCavanaugh/learn-a

This repo has a fair bit of duplication where projects need to write down their dependencies in package.json and as references (with different syntax) in tsconfig.json.

Checklist

My suggestion meets these guidelines:

• This wouldn’t be a breaking change in existing TypeScript / JavaScript code
• This wouldn’t change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn’t a runtime feature (e.g. new expression-level syntax)

[evocateur]

I’m in the process of writing an apology to the community (for a number of things) accompanying a revert of the license changes. I have been suffering a low-grade anxiety attack almost all day long. I appreciate your patience.

[RyanCavanaugh]

Due to the most common monorepo tool effectively blocking our use of it [1], I don’t think we’ll be able to do any work here without inviting potential legal problems.

FYI @satyanadella

[1] https://github.com/lerna/lerna/pull/1616

Edit: We’re back; see below.