Class AsyncResult<T, E>

constructor

• new AsyncResult<T, E>(start): AsyncResult<T, E>

• Constructs an AsyncResult from a Result or a Promise of a Result.

  Type Parameters

  • T

  • E

  Parameters

  • start: Result<T, E> | Promise<Result<T, E>>

  Returns AsyncResult<T, E>

  Example

  const ar = new AsyncResult(Promise.resolve('value'))
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andThen

• andThen<T2, E2>(mapper): AsyncResult<T2, E | E2>

• Calls mapper if the result is Ok, otherwise keeps the Err value intact. This function can be used for control flow based on Result values.

  Type Parameters

  • T2

  • E2

  Parameters

  • mapper: ((val) => Result<T2, E2> | Promise<Result<T2, E2>> | AsyncResult<T2, E2>)

    • • (val): Result<T2, E2> | Promise<Result<T2, E2>> | AsyncResult<T2, E2>

      • Parameters

        • val: T

        Returns Result<T2, E2> | Promise<Result<T2, E2>> | AsyncResult<T2, E2>

  Returns AsyncResult<T2, E | E2>

  Example

  let goodResult = Ok(1).toAsyncResult()
  let badResult = Err('boo').toAsyncResult()
  
  await goodResult.andThen(async (value) => Ok(value * 2)).promise // Ok(2)
  await goodResult.andThen(async (value) => Err(`${value} is bad`)).promise // Err('1 is bad')
  await badResult.andThen(async (value) => Ok(value * 2)).promise // Err('boo')
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map

• map<U>(mapper): AsyncResult<U, E>

• Maps an AsyncResult<T, E> to AsyncResult<U, E> by applying a function to a contained Ok value, leaving an Err value untouched.

  This function can be used to compose the results of two functions.

  Type Parameters

  • U

  Parameters

  • mapper: ((val) => U | Promise<U>)

    • • (val): U | Promise<U>

      • Parameters

        • val: T

        Returns U | Promise<U>

  Returns AsyncResult<U, E>

  Example

  let goodResult = Ok(1).toAsyncResult()
  let badResult = Err('boo').toAsyncResult()
  
  await goodResult.map(async (value) => value * 2).promise // Ok(2)
  await badResult.andThen(async (value) => value * 2).promise // Err('boo')
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promise