# Async `deft/stdext/async` provides fan-out helpers over the language's `@async` / `await` futures. Each future already runs concurrently on the event loop or its own thread (`deftask`, `defworker`, `sqlite/*-async`, `os/run-async`); these helpers start a batch and collect the results in order.

import "deft/stdext/async" as async
from "deft/stdext/async" import @{ await-all map-concurrently }

## API | Def | Signature | Description | |---|---|---| | `await-all` | `{| futures |}` | Resolve every future in order, returning results positionally; non-futures pass through | | `map-concurrently` | `{| items fn |}` | Call `fn` on every item concurrently (each call becomes a future), then `await-all` | | `each-concurrently` | `{| items fn |}` | Same fan-out for side effects; results are discarded | | `filter-futures` | `{| items |}` | Keep only the Future values in a mixed list |

set results [$urls |> async/map-concurrently { fetch-data $it }]

set futures [map $urls { [fetch-data $it] }]
set results [await-all $futures]

[async/each-concurrently $urls { log/info "fetched " [await [fetch-data $it]] }]

## Semantics There is no pool: concurrency comes from the futures themselves, and `await-all` simply joins in positional order. Error semantics are the natives' — a `deftask` body that throws resolves with the error string instead of rethrowing at `await`. ## See Also - Concurrency — `deftask` / `await` fundamentals - Tasks — streams, `future-ready?`, `task/stream-*` - defworker — persistent worker runtimes