> For AI agents: the complete documentation index is available at /byethrow/llms.txt, the full documentation bundle is available at /byethrow/llms-full.txt. # Namespace: Result Re-exports core Result-handling utilities under two convenient namespaces: - `Result`: Verbose and explicit usage - `R`: Shorthand alias for more concise code ## Examples **Basic Usage** ```ts import { Result } from '@praha/byethrow'; const validateId = (id: string) => { if (!id.startsWith('u')) { return Result.fail(new Error('Invalid ID format')); } return Result.succeed(); }; const findUser = Result.fn({ try: (id: string) => { return { id, name: 'John Doe' }; }, catch: (error) => new Error('Failed to find user', { cause: error }), }); const result = Result.pipe( Result.succeed('u123'), Result.andThrough(validateId), Result.andThen(findUser), ); if (Result.isSuccess(result)) { console.log(result.value); // User found: John Doe } ``` **Shorthand Usage** ```ts import { R } from '@praha/byethrow'; const validateId = (id: string) => { if (!id.startsWith('u')) { return R.fail(new Error('Invalid ID format')); } return R.succeed(); }; const findUser = R.fn({ try: (id: string) => { return { id, name: 'John Doe' }; }, catch: (error) => new Error('Failed to find user', { cause: error }), }); const result = R.pipe( R.succeed('u123'), R.andThrough(validateId), R.andThen(findUser), ); if (R.isSuccess(result)) { console.log(result.value); // User found: John Doe } ``` ## Core Types | Type Alias | Description | | ------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------- | | [Failure](/byethrow/api/types/Result.Failure.md) | Represents a failed result. | | [Result](/byethrow/api/types/Result.Result.md) | A union type representing either a success or a failure. | | [ResultAsync](/byethrow/api/types/Result.ResultAsync.md) | An asynchronous variant of [Result](/byethrow/api/types/Result.Result.md), wrapped in a `Promise`. | | [ResultFor](/byethrow/api/types/Result.ResultFor.md) | Resolves to the appropriate Result type (sync or async) based on the input type. | | [ResultMaybeAsync](/byethrow/api/types/Result.ResultMaybeAsync.md) | A result that may be either synchronous or asynchronous. | | [Success](/byethrow/api/types/Result.Success.md) | Represents a successful result. | ## Infer Types | Type Alias | Description | | ---------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- | | [InferFailure](/byethrow/api/types/Result.InferFailure.md) | Infers the [Failure](/byethrow/api/types/Result.Failure.md) value type `E` from a Result or a function returning a Result. | | [InferSuccess](/byethrow/api/types/Result.InferSuccess.md) | Infers the [Success](/byethrow/api/types/Result.Success.md) value type `T` from a Result or a function returning a Result. | ## Creators | Function | Description | | ---------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [do](/byethrow/api/functions/Result.do.md) | Alias for `succeed({})`. Commonly used as a neutral base value in functional chains or monadic pipelines. | | [fail](/byethrow/api/functions/Result.fail.md) | Creates a [Failure](/byethrow/api/types/Result.Failure.md) result from a given error. | | [fn](/byethrow/api/functions/Result.fn.md) | Wraps a function that may throw and returns a new function that returns a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). | | [succeed](/byethrow/api/functions/Result.succeed.md) | Creates a [Success](/byethrow/api/types/Result.Success.md) result from a given value. | | [try](/byethrow/api/functions/Result.try.md) | Executes a function that may throw and wraps the result in a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). | ## Combinators | Function | Description | | -------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [andThen](/byethrow/api/functions/Result.andThen.md) | Chains the next computation using the success value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). If the original result is a [Failure](/byethrow/api/types/Result.Failure.md), it is returned unchanged. Otherwise, the provided function is called, and its result is returned as-is. | | [andThrough](/byethrow/api/functions/Result.andThrough.md) | Runs an additional computation using the success value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md), but **returns the original result** if the additional computation is successful. | | [bind](/byethrow/api/functions/Result.bind.md) | Chains another [Result](/byethrow/api/types/Result.Result.md)-producing computation and **merges its success value** into the existing object under the specified key. | | [inspect](/byethrow/api/functions/Result.inspect.md) | Executes a side effect function on the success value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md), without modifying the original result. This is useful for debugging, logging, or performing other side effects while maintaining the original value and error state. | | [inspectError](/byethrow/api/functions/Result.inspectError.md) | Executes a side effect function on the error value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md), without modifying the original result. This is useful for debugging, logging, or performing other side effects while maintaining the original value and error state. | | [map](/byethrow/api/functions/Result.map.md) | Applies a transformation function to the success value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). If the input is a [Failure](/byethrow/api/types/Result.Failure.md), it will be returned unchanged. | | [mapError](/byethrow/api/functions/Result.mapError.md) | Applies a transformation function to the error value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). If the input is a [Success](/byethrow/api/types/Result.Success.md), it will be returned unchanged. | | [orElse](/byethrow/api/functions/Result.orElse.md) | Chains the next computation using the error value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). If the original result is a [Success](/byethrow/api/types/Result.Success.md), it is returned unchanged. Otherwise, the provided function is called, and its result is returned as-is. | | [orThrough](/byethrow/api/functions/Result.orThrough.md) | Runs an additional computation using the error value of a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md), but **returns the original failure** if the additional computation is successful. | ## Unwraps | Function | Description | | ------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------- | | [unwrap](/byethrow/api/functions/Result.unwrap.md) | Extracts the success value from a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). | | [unwrapError](/byethrow/api/functions/Result.unwrapError.md) | Extracts the error value from a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md). | ## Assertions | Function | Description | | ---------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [assertFailure](/byethrow/api/functions/Result.assertFailure.md) | Asserts that a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md) is a [Failure](/byethrow/api/types/Result.Failure.md) and returns it. This function requires that the result's success type is `never`, meaning the result is guaranteed to be a [Failure](/byethrow/api/types/Result.Failure.md) at the type level. If the result is a [Success](/byethrow/api/types/Result.Success.md) at runtime, throws an error. | | [assertSuccess](/byethrow/api/functions/Result.assertSuccess.md) | Asserts that a [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md) is a [Success](/byethrow/api/types/Result.Success.md) and returns it. This function requires that the result's error type is `never`, meaning the result is guaranteed to be a [Success](/byethrow/api/types/Result.Success.md) at the type level. If the result is a [Failure](/byethrow/api/types/Result.Failure.md) at runtime, throws an error. | ## Type Guards | Function | Description | | -------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------ | | [isFailure](/byethrow/api/functions/Result.isFailure.md) | Type guard to check if a [Result](/byethrow/api/types/Result.Result.md) is a [Failure](/byethrow/api/types/Result.Failure.md). | | [isResult](/byethrow/api/functions/Result.isResult.md) | Type guard to check if a value is a [Result](/byethrow/api/types/Result.Result.md). | | [isSuccess](/byethrow/api/functions/Result.isSuccess.md) | Type guard to check if a [Result](/byethrow/api/types/Result.Result.md) is a [Success](/byethrow/api/types/Result.Success.md). | ## Utilities | Function | Description | | ------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [collect](/byethrow/api/functions/Result.collect.md) | Processes multiple [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md) values into a single result. If all results are [Success](/byethrow/api/types/Result.Success.md), returns a [Success](/byethrow/api/types/Result.Success.md) containing all values. If any result is a [Failure](/byethrow/api/types/Result.Failure.md), returns a [Failure](/byethrow/api/types/Result.Failure.md) containing an array of all errors. | | [parse](/byethrow/api/functions/Result.parse.md) | Parses a value using a [Standard Schema](https://github.com/standard-schema/standard-schema) compatible schema. Returns a [Result](/byethrow/api/types/Result.Result.md) with the parsed value on success or validation errors on failure. | | [pipe](/byethrow/api/functions/Result.pipe.md) | Applies a sequence of functions to a value, from left to right. | | [sequence](/byethrow/api/functions/Result.sequence.md) | Processes multiple [Result](/byethrow/api/types/Result.Result.md) or [ResultAsync](/byethrow/api/types/Result.ResultAsync.md) values into a single result. If all results are [Success](/byethrow/api/types/Result.Success.md), returns a [Success](/byethrow/api/types/Result.Success.md) containing all values. If any result is a [Failure](/byethrow/api/types/Result.Failure.md), immediately stops processing and returns a [Failure](/byethrow/api/types/Result.Failure.md) with that single error. |