byethrow
  • English

      • prefer-result-async

      Enforces use of ResultAsync<T, E> instead of Promise<Result<T, E>>.

      Rule details

      ResultAsync<T, E> is an alias for Promise<Result<T, E>>. Using the dedicated type alias is shorter, more expressive, and signals clearly that the function returns a Result-wrapped async value. This rule auto-fixes violations.

      Incorrect

      import { 
      type Result = Promise<Result.Result<string, Error>>
      Result       } from '@praha/byethrow';      

// ❌ using Promise<Result<...>>
type 
      type Result = Promise<Result.Result<string, Error>>
      Result       = 
      interface Promise<T>
      Represents the completion of an asynchronous operation
      Promise      <
      import Result
      Result      .
      type Result<T, E> = Result.Success<T> | Result.Failure<E>
      A union type representing either a success or a failure.
      @typeParamT  - The type of the Success value.@typeParamE  - The type of the Failure value.@example
      import { Result } from '@praha/byethrow';

const doSomething = (): Result.Result<number, string> => {
  return Math.random() > 0.5
    ? { type: 'Success', value: 10 }
    : { type: 'Failure', error: 'Oops' };
};
      @categoryCore  Types
      Result      <string, Error>>;

      Correct

      import { 
      type Result = Promise<Result.Result<string, Error>>
      Result       } from '@praha/byethrow';      

// ✅ using ResultAsync
type 
      type Result = Promise<Result.Result<string, Error>>
      Result       = 
      import Result
      Result      .
      type ResultAsync<T, E> = Promise<Result.Result<T, E>>
      An asynchronous variant of
Result
, wrapped in a Promise.
      @typeParamT  - The type of the Success value.@typeParamE  - The type of the Failure value.@example
      import { Result } from '@praha/byethrow';

const fetchData = async (): Result.ResultAsync<string, Error> => {
  try {
    const data = await fetch('...');
    return { type: 'Success', value: await data.text() };
  } catch (err) {
    return { type: 'Failure', error: err as Error };
  }
};
      @categoryCore  Types
      ResultAsync      <string, Error>;