Suggestion

🔍 Search Terms

Inference
Template Literal Types
Subtypes

✅ Viability 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, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

I'd like to be able to infer a subtype from a template literal type. For example:

const canExtend: `myString.${number}` extends `${infer Key}.${number}` ? true : false = true;

📃 Motivating Example

This will allow cross-matching between Values and Paths when traversing an object with dot notation.

💻 Use Cases

See line 35, in this Playground