microsoft / microsoft/TypeScript

Expose type level api

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Description

Search Terms

plugin, type, intrinsic, api

Suggestion

Now we have intrinsic type for template literal type.

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Could we release the type level api for customize the behavior of type?

Use Cases

For example

type ToNumber<T extends string> = intrinsic

type Plus<T extends number, U extends number> = intrinsic

Related:

  • #26382
  • #16607

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. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
  • This feature would agree with the rest of TypeScript's Design Goals.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No implementation files, tests, or entry points are named. Start by reading the proposal and related issues #26382 and #16607, then determine the design and scope of a public type-level API for custom intrinsic types; done would require an agreed specification and implementation plan.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
20/100

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