Ts Core

Description

This is a project designed to provide a foundation for a more rigid type system in TypeScript. It is designed to be similar to the type system in Rust, but abiding by the limitations of TypeScript.

Installation

npm install @ellefe/ts-core

Usage

Result

The Result type is a type that represents either a successful value or an error. It is similar to the Result type in Rust. The Result type has two variants: Ok and Err. The Ok variant contains the successful value, and the Err variant contains the error value.

This type is useful for denoting that an operation may fail and returning additional information about the failure. For example, a function that parses a string into a number may return an error if the string is not a valid number.

There are a number of different methods available on the Result type that allow for chaining operations on the result.

Basic Usage - Result

function divide(a: number, b: number): Result<number, string> {
  if (b === 0) {
    return err('Cannot divide by zero');
  }

  return ok(a / b);
}

const result = divide(10, 2); // Ok: 5
const error = divide(10, 0); // Err: Cannot divide by zero

Chaining - Result

function multiply(a: number, b: number): number {
  return a * b;
}

const result = divide(10, 2)
  .map((result) => multiply(result, 2)); // Ok: 10
const error = divide(10, 0)
  .map((result) => multiply(result, 2)); // Err: Cannot divide by zero

Async Chaining - Result

const user = await UserImpl.getById(123)
  .andThen((user) => user.update({ name: 'John Doe' }))
  .andThen((user) => user.save())

if (user.isOk()) {
  console.log('Saved user', user.inner().name)
} else {
  console.error(user.inner().message)
}

For more complete examples see the examples directory.

Option

The Option type is a type that represents either a value or no value. It is similar to the Option type in Rust. The Option type has two variants: Some and None. The Some variant contains the value, and the None variant contains no value.

This type is useful for denoting that an operation may or may not return a value and no other information is relevant. For example, a function that returns the first element of an array may return None if the array is empty.

Just like the result type, there are a number of different methods available on the Option type that allow for chaining operations on the option.

Basic Usage - Option

const someValue = some(10); // Some: 10
const noneValue = none(); // None

Chaining - Option

const someValue = some(10)
  .map((value) => value * 2); // Some: 20
const noneValue = none()
  .map((value) => value * 2); // None

Async Chaining - Option

const user = await UserImpl.getById(123)
  .ok()
  .map((user) => user.name)
  .map((name) => name.toUpperCase())