maybe.ts

// License: Public domain
// see: https://creativecommons.org/publicdomain/zero/1.0/deed.en

interface Option<T> {
  value: T | null;
}

/**
 * First-class None subtype for a value that is Maybe.None.
 */
export class None<T> implements Option<null> {
  public value = null
}

/**
 * First class Some<T> subtype for a value that is Maybe<T>Some(value).
 */
export class Some<T> implements Option<T> {
  public value: T;
  public constructor(value: T) {
    this.value = value;
  }
}

/**
 * Factory wrapper of Some, None, so that pattern matching is possible.
 */
export default class Maybe {
  public static Some<T>(value: T): Some<T> {
    return new Some<T>(value);
  }
  public static None(): Maybe {
    return new None() as Maybe;
  }
}