Task

1 min read

Import: import system.task;

Read the structured concurrency guide for lifetimes, cancellation, backpressure, and worker execution.

Task

Structured local async scopes and bounded maps, with explicit low-level worker spawning.

public class Task

scope

Runs a structured async region and joins all children on success, failure, or cancellation.

public static async fun scope<T, E>(
    body: fun(TaskScope<E>): Future<Result<T, TaskFailure<E>>>,
    timeout_ms: int = 0,
    token: Option<CancellationToken> = Option.None
): Result<T, TaskFailure<E>>

spawn

Runs one synchronous function on a separate worker; use scope.spawn_on for structured CPU jobs. Panics when the worker crashes before replying; TaskPool.dispatch and scope children report that as TaskPoolError.WorkerCrashed instead.

public static async fun spawn<TOut: shared>(
    body: fun(): TOut,
    token: Option<CancellationToken> = Option.None
): TOut

spawn_async

Runs an async function on a separate worker; local async scope children need no worker. Panics when the worker crashes before replying.

public static async fun spawn_async<TOut: shared>(
    body: fun(): Future<TOut>,
    token: Option<CancellationToken> = Option.None
): TOut

map

Maps with bounded local async concurrency and returns values in input order.

public static async fun map<T, U, E>(
    items: T[],
    body: fun(T): Future<Result<U, E>>,
    concurrency: int,
    token: Option<CancellationToken> = Option.None
): Result<U[], TaskFailure<E>>

for_each

Applies an async operation with bounded concurrency; successful child values are discarded.

public static async fun for_each<T, U, E>(
    items: T[],
    body: fun(T): Future<Result<U, E>>,
    concurrency: int,
    token: Option<CancellationToken> = Option.None
): Result<Unit, TaskFailure<E>>