#Function: mapError()

Applies a transformation function to the error value of a Result or ResultAsync. If the input is a Success, it will be returned unchanged.

#Type Param

The input Result or ResultAsync.

#Type Param

The transformed error value type.

#Examples

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

const result = Result.pipe(
  Result.fail('NotFound'),
  Result.mapError((error) => new Error(error)),
);
// { type: 'Failure', error: Error('NotFound') }

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

const result = Result.pipe(
  Result.succeed(123),
  Result.mapError((error) => new Error(error)),
);
// { type: 'Success', value: 123 }

#See

pipe - It is recommended to use this function with the pipe function for better readability and composability.

#Call Signature

mapError<R1, E2>(fn): (result) => ResultFor<R1, InferSuccess<R1>, E2>

Defined in: functions/map-error.ts:44

#Type Parameters

#R1

R1 extends ResultMaybeAsync<any, any>

#E2

E2

#Parameters

#fn

(a) => E2

#Returns

(result): ResultFor<R1, InferSuccess<R1>, E2>

#Parameters

#result

R1

#Returns

ResultFor<R1, InferSuccess<R1>, E2>

#Call Signature

mapError<E1, E2>(fn): <R1>(result) => ResultFor<R1, InferSuccess<R1>, E2>

Defined in: functions/map-error.ts:45

#Type Parameters

#E1

E1

#E2

E2

#Parameters

#fn

(a) => E2

#Returns

<R1>(result): ResultFor<R1, InferSuccess<R1>, E2>

#Type Parameters

#R1

R1 extends ResultMaybeAsync<any, E1>

#Parameters

#result

R1

#Returns

ResultFor<R1, InferSuccess<R1>, E2>