byethrow
  • English

      • Function: unwrapError()

      Extracts the error value from a Result or ResultAsync.

      If the input is a Success, it will throw the success value or return the default value if provided.

      Type Param

      R

      The input Result or ResultAsync.

      Type Param

      T

      The default value type (optional).

      Examples

      Failure Case (without default)

      import { 
      import Result
      Result       } from '@praha/byethrow';      

const 
      const result: Result.Result<number, string>
      result      : 
      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      <number, string> = 
      import Result
      Result      .
      const fail: <"Oops">(error: "Oops") => Result.Result<never, "Oops"> (+1 overload)
      fail      ('Oops');      
const 
      const error: string
      error       = 
      import Result
      Result      .
      const unwrapError: <Result.Result<number, string>>(result: Result.Result<number, string>) => string (+3 overloads)
      unwrapError      (
      const result: Result.Result<number, string>
      result      ); // 'Oops'

      Failure Case (with default)

      import { 
      import Result
      Result       } from '@praha/byethrow';      

const 
      const result: Result.Result<number, string>
      result      : 
      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      <number, string> = 
      import Result
      Result      .
      const fail: <"Oops">(error: "Oops") => Result.Result<never, "Oops"> (+1 overload)
      fail      ('Oops');      
const 
      const error: string
      error       = 
      import Result
      Result      .
      const unwrapError: <Result.Result<number, string>, "default">(result: Result.Result<number, string>, defaultValue: "default") => string (+3 overloads)
      unwrapError      (
      const result: Result.Result<number, string>
      result      , 'default'); // 'Oops'

      Success Case (without default)

      import { 
      import Result
      Result       } from '@praha/byethrow';      

const 
      const result: Result.Result<number, string>
      result      : 
      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      <number, string> = 
      import Result
      Result      .
      const succeed: <100>(value: 100) => Result.Result<100, never> (+1 overload)
      succeed      (100);      
const 
      const error: string
      error       = 
      import Result
      Result      .
      const unwrapError: <Result.Result<number, string>>(result: Result.Result<number, string>) => string (+3 overloads)
      unwrapError      (
      const result: Result.Result<number, string>
      result      ); // throws 100

      Success Case (with default)

      import { 
      import Result
      Result       } from '@praha/byethrow';      

const 
      const result: Result.Result<number, string>
      result      : 
      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      <number, string> = 
      import Result
      Result      .
      const succeed: <100>(value: 100) => Result.Result<100, never> (+1 overload)
      succeed      (100);      
const 
      const error: string | 0
      error       = 
      import Result
      Result      .
      const unwrapError: <Result.Result<number, string>, 0>(result: Result.Result<number, string>, defaultValue: 0) => string | 0 (+3 overloads)
      unwrapError      (
      const result: Result.Result<number, string>
      result      , 0); // 0

      See

      assertFailure - When used with assertFailure, you can safely unwrap the Result.

      Call Signature

      unwrapError<R>(result): true extends HasPromise<R> ? Promise<InferFailure<R>> : InferFailure<R>

      Type Parameters

      R

      R extends ResultMaybeAsync<any, any>

      Parameters

      result

      R

      Returns

      true extends HasPromise<R> ? Promise<InferFailure<R>> : InferFailure<R>

      Call Signature

      unwrapError<R, T>(result, defaultValue): true extends HasPromise<R> ? Promise<T | InferFailure<R>> : T | InferFailure<R>

      Type Parameters

      R

      R extends ResultMaybeAsync<any, any>

      T

      T

      Parameters

      result

      R

      defaultValue

      T

      Returns

      true extends HasPromise<R> ? Promise<T | InferFailure<R>> : T | InferFailure<R>

      Call Signature

      unwrapError<R>(): (result) => true extends HasPromise<R> ? Promise<InferFailure<R>> : InferFailure<R>

      Type Parameters

      R

      R extends ResultMaybeAsync<any, any>

      Returns

      (result) => true extends HasPromise<R> ? Promise<InferFailure<R>> : InferFailure<R>

      Call Signature

      unwrapError<R, T>(defaultValue): (result) => true extends HasPromise<R> ? Promise<T | InferFailure<R>> : T | InferFailure<R>

      Type Parameters

      R

      R extends ResultMaybeAsync<any, any>

      T

      T

      Parameters

      defaultValue

      T

      Returns

      (result) => true extends HasPromise<R> ? Promise<T | InferFailure<R>> : T | InferFailure<R>