microsoft / microsoft/TypeScript
Write a function to define types.
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Suggestion
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Description
Search Terms
type defination, functional type defination, meta, meta programming, dynamic type declaration
Suggestion
Write a function to define types.
Use Cases
Build a more complex type.
Examples
type MyType<T extends string>{
if(T extends 'a'){
return 'a' //type 'a'
}
if(T extends 'b'){
return 'b' //type 'b'
}
return string
}
Checklist
My suggestion meets these guidelines:
- [x ] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x ] This wouldn't change the runtime behavior of existing JavaScript code
- [x ] This could be implemented without emitting different JS based on the types of the expressions
- [x ] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
- [x ] This feature would agree with the rest of TypeScript's Design Goals.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue names no files, tests, or entry points. Read the issue discussion first to clarify the proposed type-level function's syntax and semantics, then identify the relevant compiler area and define tests that establish the intended behavior.
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
- 25/100