Write a function to define types.

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.

L’issue ne mentionne aucun fichier, test ni point d’entrée. Lisez d’abord la discussion de l’issue afin de clarifier la syntaxe et la sémantique de la fonction proposée au niveau des types, puis identifiez la partie concernée du compilateur et définissez des tests qui établissent le comportement attendu.