adregan

import { Result } from "./result";

describe("Result", () => {
  describe("creating", () => {
    describe("Result.ok()", () => {
      test("it returns an ok result", () => {
        const result = Result.ok("I'm good");
        expect(result.isOk()).toBeTruthy();
      });

adregan

import { Machine } from "./machine";
import { Context, State } from "./models";

describe("Machine", () => {
  describe("Machine.create(state)", () => {
    test("it returns an instance of state machine", () => {
      const machine = Machine.create({ value: "saying.hello", context: {} });
      expect(machine).toBeInstanceOf(Machine);
    });
  });

adregan

const _Some = Symbol("some");
const _None = Symbol("none");

type Some<T> = {
  type: typeof _Some;
  value: T;
};

type None = {
  type: typeof _None;