Walk That Type

Debugging complex TypeScript types is painful, because you can't simply put log statements in them and the obscure syntax doesn't help. Introducing Walk That Type: a tool that lets you paste or write any type, then step through it while explaining what happens at each step!

🚧 Warning: this project is still in early development stage. It might include bugs and missing features (see ROADMAP to see what's still coming).

Contributing

1. Fork this repo
2. Create a new branch, push your changes, and open a PR.

Feel free to report any issues or feature requests using Github issues.

Development setup

1. Install pnpm
2. Run pnpm install
3. Run pnpm dev to start the dev server
4. Run pnpm test to run tests (in watch mode)

Implementing new features:

• Make sure mapASTToTypeNodes handles parsing syntax for this feature, if not, add it. This requires adding a new TypeNode variant. Fill missing cases in functions that use TypeNode (use pnpm check:types to find all these places).
• Add tests and implement evalT for this feature.
• Add tests and implement extendsT for this feature (if needed).
• Add traverse logic in traverse function.
• In eval-tree.ts add new cases in calculateNextStep and chooseNodeToEval.
• Finally, update EvalDescription component.

Implementing built-in types

To add a missing built-in type (e.g. Pick) you just need to implement it in the global-types.ts files according to GlobalTypeFn type.