Overview

Lazy, composable and cancelable async computations

API

Installation

yarn

yarn add @w5s/task

pnpm

pnpm add @w5s/task

npm

npm install @w5s/task

Motivation

A Task<Value, Error> is a lazy computation that will be evaluated later. Unlike Promises, Tasks:

• Are lazy: Nothing happens until you explicitly run them
• Are composable: Chain operations without triggering execution
• Are cancelable: Stop running tasks when no longer needed
• Return Results: Always resolve to Result<Value, Error>, making error handling explicit

This makes Tasks ideal for:

• Side effects management
• Complex async workflows
• Testable async code
• Resource management with cancellation

Quick Start

import { Task } from '@w5s/task';

// Create a task that generates a random number
function randomNumber() {
  return Task.create(() => Task.ok(Math.random()));
}

// Create a task that logs a value
function log(value: unknown) {
  return Task.create(() => Task.ok(console.log(value)));
}

// Compose tasks
export function main() {
  const randomValueTask = randomNumber();
  const squareValueTask = Task.map(randomValueTask, (value) => value * value);
  return Task.andThen(squareValueTask, log);
}

// Run at the edge of your program
void Task.run(main());