[learn FP with Kirby using `fp-ts`] Task

task.ts

import { describe } from "../utils";

/**
 * Task
 * ===
 * A task is a function that returns a promise which is expected to never be rejected.
 */

/**
 * Why use Task?
 */

const asyncFunction = async () => Promise.resolve();

describe(`
    when you have an operation that can fail,
    but is handled by reducing both the success and failure outcomes into a single type.
`, () => {
  const boolTask: () => Promise<boolean> = async () => {
    try {
      await asyncFunction();
      return true;
    } catch (err) {
      return false;
    }
  };
});

import { Task } from "fp-ts/lib/Task";

describe(`Use Task implement`, () => {
  const boolTask: Task<boolean> = async () => {
    try {
      await asyncFunction();
      return true;
    } catch (err) {
      return false;
    }
  };
});

/**
 * Constructor
 */

import * as T from "fp-ts/lib/Task";

describe("Task Constructor", () => {
  const foo = "asdf";
  const bar = T.of(foo);

  // Same as
  const baz: Task<string> = () => Promise.resolve("abc");
});