result

Description

A Result based error handling library. Inspired by Rust's Result type and neverthrow.

This package aims to simplify neverthrow's API while still offering the result type-safety.

Installation

npm install @l3dev/result

pnpm add @l3dev/result

Documentation

ok

Creates an Ok object, alias: Result.ok

ok<T>(value: T): Ok<T>

Example

import { ok } from "@l3dev/result";

const result = ok(42);

result.ok; // true
result.value; // 42

Use NONE for a void ok result: Ok<void>

err

Create an Err object, alias: Result.err

err<T>(type: T): Err<T, null>
err<T, D>(type: T, context: D): Err<T, D>

Example

import { err } from "@l3dev/result";

const result = err("error");

result.ok; // false
result.type; // 'error'
result.context; // null

const resultWithContext = err("error", { message: "Something went wrong" });

result.ok; // false
result.type; // 'error'
result.context; // { message: 'Something went wrong' }

Result.isOk

Returns true if the result is an Ok object

isOk(result: ReturnResult<any, any>): boolean

Result.isErr

Returns true if the result is an Err object

isErr(result: ReturnResult<any, any>): boolean

Result.fn

Wraps a function requiring that the ReturnType be a ReturnResult type.

fn<T, F extends (...) => T>(fn: F): F

Example

import { ok, err, Result } from "@l3dev/result";

const myFunction = Result.fn((roll: number) => {
	if (roll < 1 || roll > 6) {
		return err("Invalid roll");
	}
	return ok(roll);
});

const result = myFunction(3); // Ok<3> | Err<"Invalid roll", null>

Result.fromPromise

Catches any errors thrown by a promise into Err objects.

fromPromise<T>(promise: T): Promise<ReturnResult<Awaited<T>, ResultErrorDefinition<null, { error: TError }>>>

Result.unwrapOrDefault

Unwraps the result, returning the value if it is an Ok object, or the default value if it is an Err object.

unwrapOrDefault<T>(result: ReturnResult<T, any>, defaultValue: T): T