@justmiracle/result

A minimal implementation of the Result type in TypeScript. Allowing you to handle success and error states in a more explicit and structured way.

Installation

npm install @justmiracle/result

yarn add @justmiracle/result

pnpm add @justmiracle/result

bun add @justmiracle/result

Docs

• API
• Creating a Result
• Checking Result Type
• Unwrapping Result
• Transforming Result

API

// A result is either successful or an error
type Result<T> = Ok<T> | Err;

// A successful result contains a value and null for error
type Ok<T> = { value: T; error: null };

// An error result contains null for value and an error
type Err = { value: null; error: Error };

Creating a Result

You can create a result using the ok or err function:

import { ok, err } from '@justmiracle/result';

const successResult: Result<number> = ok(42);
// { value: 42, error: null }

const errorResult: Result<number> = err(new Error('Something went wrong'));
// { value: null, error: Error }

// error can be anything, if the function detect that it's not an error it will be converted to an error
const errorResult: Result<number> = err('Something went wrong');
// { value: null, error: Error } the same as above

Checking Result Type

You can check if a result is successful using the isOk function:

if (isOk(successResult)) {
  console.log('Success:', successResult.value);
} else {
  console.error('Error:', successResult.error.message);
}

You can check if a result is an error using the isErr function:

if (isErr(errorResult)) {
  console.error('Error:', errorResult.error.message);
} else {
  console.log('Success:', errorResult.value);
}

Unwrapping Result

You can unwrap the value from a result type using unwrapOr, this will return the value if the result is successful or a default value if it's an error:

const resultOne = ok(42);
const value = unwrapOr(resultOne, 12); // 42

const resultTwo = err('Something went wrong');
const value = unwrapOr(resultTwo, 12); // 12 default value

You can also unwrap the value from a successful result using unwrap, which throws an error for an error result:

Warning

This will throw an error if the result is an error, so make sure to handle it properly.

const resultOne = ok(42);
const value = unwrap(resultOne); // 42

const resultTwo = err('Something went wrong');
const value = unwrap(resultTwo); // throws an error

Transforming Result

You can apply a function to the value inside a successful result using map:

const successResult = ok(42);
const mappedResult = map(successResult, value => value * 2);
// { value: 84, error: null }

Roadmap

• Typesafe error handling
• pipe function

Contributing

Contributions are welcome, feel free to open an issue or a pull request.🍀