Creating Tasks

Different ways to create Task instances

API

Overview

Tasks can be created in multiple ways depending on your use case. The main entry point is Task.create, but there are also convenience methods for common patterns.

Task.create

The primary way to create a task with custom logic:

Synchronous

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

// Synchronous computation
const randomNext = Task.create(() => Task.ok(Math.random()));

// Execute synchronously
const result = Task.run(randomNext); // Result.Ok([generated number])

Asynchronous

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

// With error handling
const fetchTask = Task.create(async () => {
  try {
    const response = await fetch('/api/data');
    return Task.ok(await response.json());
  } catch (error) {
    return Task.error(new NetworkError({ cause: error }));
  }
});

// Execute asynchronously
const result = await Task.run(fetchTask); // Result.Ok([json response]) or Result.Error(NetworkError())

Task.resolve / Task.reject

Create tasks that immediately resolve or reject:

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

// A task that resolves with a value
const resolvedTask = Task.resolve(42);

// A task that rejects with an error
const rejectedTask = Task.reject(new Error('Something went wrong'));

Task.ok / Task.error

Shorthand for creating Result objects within tasks:

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

const myTask = Task.create(() => {
  const random = Math.random();
  if (random > 0.5) {
    return Task.ok(random);
  }
  return Task.error('Too low');
});

Task.tryCall

Safely wrap functions that might throw:

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

const parseJSON = (text: string) =>
  Task.tryCall(
    () => JSON.parse(text),
    (error) => new ParseError({ message: 'Invalid JSON', cause: error })
  );

Task.from (Advanced)

Lower-level API for creating tasks with full control over execution:

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

const delayedTask = Task.from(({ resolve, reject, canceler }) => {
  const timeoutId = setTimeout(() => resolve(42), 1000);
  
  // Setup cancellation
  canceler.addEventListener('abort', () => clearTimeout(timeoutId));
});