TypeScript Snippets

typescript-snippets.ts

/** ===========================================================================
 * TypeScript Result type!
 *
 * This is a Result type inspired by Rust.
 *
 * Reference: https://doc.rust-lang.org/rust-by-example/error/result.html
 *
 * The Result type allow type checking on operations which may fail, since
 * in TypeScript there is no way to convey type information in functions which
 * may "throw" an error.
 * ============================================================================
 */

export interface IOk<T> {
  value: T;
  error?: undefined;
}

export interface IErr<E> {
  error: E;
  value?: undefined;
}

/**
 * Ok type constructor class.
 */
export class Ok<T> implements IOk<T> {
  value: T;
  error = undefined;

  static of<U>(value: U): Ok<U> {
    return new Ok(value);
  }

  constructor(value: T) {
    this.value = value;
  }
}

/**
 * Err type constructor class.
 */
export class Err<E> implements IErr<E> {
  value: undefined;
  error: E;

  static of<U>(value: U): Err<U> {
    return new Err(value);
  }

  constructor(error: E) {
    this.error = error;
  }
}

export type Result<T, E> = IOk<T> | IErr<E>;
  
/**
 * Artificially wait the provided amount of time.
 */
export const wait = async (time = 1000) => {
  await new Promise((resolve, reject) => setTimeout(resolve, time));
};

/** ===========================================================================
 * Inspired by the Result Option type.
 *
 * https://doc.rust-lang.org/rust-by-example/std/option.html
 * ============================================================================
 */

export interface ISome<T> {
  value: T;
  some: true;
}

export interface INone {
  some: false;
}

/**
 * Some type constructor class.
 */
export class Some<T> implements ISome<T> {
  value: T;
  some: true = true;

  static of<U>(value: U): Some<U> {
    return new Some(value);
  }

  constructor(value: T) {
    this.value = value;
  }
}

/**
 * None type constructor class.
 */
export class None implements INone {
  some: false = false;

  static of(): INone {
    return new None();
  }
}

export type Option<T> = ISome<T> | INone;