OOptional - Optional type for your OOP needs

OOptional is a TypeScript library that provides an optional type that fits nicely with Object Oriented Programming. It provides a way to handle optional values without resorting to null or undefined.

Installation

To install the library, you can use npm:

npm install ooptional

Usage

Importing

import { Optional, Option } from "ooptional";

Creating an Optional

const optional: Optional<string> = Optional.ofNullable("Hello, world!");

// or
const some: Some<string> = Optional.some("Hello, world!");
const someAsOptional: Optional<string> = Optional.some("Hello, world!");

// or

const none: None<string> = Optional.none();
const noneAsOptional: Optional<string> = Optional.none();

Checking if an Optional has a value

const optional: Optional<string> = Optional.ofNullable("Hello, world!");

if (optional.isSome()) {
  console.log(
    `$It automatically inferred the type as Some<string> and can access the value using the get() method: ${optional.get()}`
  );
} else {
  console.log("It is None");
}

Option class

The Option class has the following methods:

• isNone(): Returns false as this is the Some variant of Option.
• isSome(): Returns true as this is the Some variant of Option.
• unwrap(error?: string | Error): Returns the value if it exists, otherwise throws the provided error.
• getOrElse(defaultValue: T): Returns the value if it exists, otherwise returns the default value.
• orElse(value: Optional<T>): Returns the current Some instance.
• map<U>(f: (value: T) => U): Applies a function to the contained value and returns a new Optional instance with the result.
• mapAsync<U>(f: (value: T) => Promise<U>): Applies an asynchronous function to the contained value and returns a new Optional instance with the result.
• filter(predicate: (value: T) => boolean): Applies a predicate to the contained value and returns an Optional instance depending on the predicate result.
• filterAsync(predicate: (value: T) => Promise<boolean>): Applies an asynchronous predicate to the contained value and returns an Optional instance depending on the predicate result.
• equals(other: Optional<T>, comparator?: (a: T, b: T) => boolean): Checks if the current Optional instance is equal to another one.

Some class

The Some class is one of the variants of Option. It represents a value that exists. It has similar methods to None, but they behave differently as they have a value to work with.

• get(): Returns the value if it exists, otherwise throws an error.
• All the methods from Option.

None class

The None class is the other variant of Option. It represents an absence of value. It has similar methods to Some, but they behave differently as they don't have a value to work with.

• All the methods from Option.

Contributing

Building

To build the project, run the following command:

pnpm run build

Testing

To run the tests, use the following command:

pnpm run test

Linting

To lint the code, run the following command:

pnpm run lint

License

This project is licensed under the MIT License.