@stopcock/async

Composable async tasks with cancellation, retry, and concurrency control.

bun add @stopcock/async

import { Task } from '@stopcock/async'
import { pipe } from '@stopcock/fp'

const fetchUser = pipe(
  Task.fromPromise(() => fetch('/api/user').then((r) => r.json())),
  Task.timeout(5000),
  Task.retry({ attempts: 3, backoff: 'exponential' }),
  Task.map((data) => data.user),
)

const result = await Task.runSafe(fetchUser)

Lazy async iteration is available from the root namespace or the focused subpath:

import { AsyncIter, Task } from '@stopcock/async'

const values = AsyncIter.from([3, 1, 2])
const mapped = AsyncIter.mapConcurrent(
  values,
  async (value, _index, signal) => {
    await fetch(`/work/${value}`, { signal })
    return value * 2
  },
  { concurrency: 2 },
)

const ordered = await Task.run(AsyncIter.collect(mapped))
// [6, 2, 4] -- output order always matches source order

What's in the box

• Task — lazy async computation that doesn't run until you call run / runSafe
• AsyncIter — lazy sync/async iterable pipelines with end-to-end cancellation
• Combinators — map, flatMap, tap, mapError, catchError, match
• Concurrency — all, allSettled, race, any, parallel, sequential
• Resilience — retry, timeout, fallback
• Flow control — throttle, debounce, rateLimit
• Collection — mapAsync, filterAsync, forEachAsync, reduceAsync, collectAsync

Docs