Timeout

withTimeout races a handler against a timer. If the handler finishes first, you get Ok(result). If the timer fires first, you get Err(void).

Basic timeout

withTimeout(constant(5_000), longRunningStep)

The first argument is an action that produces the timeout duration in milliseconds. constant(5_000) is the simplest case — a fixed 5-second timeout.

The output is Result<TOutput, void>:

• Ok(result) if the handler completes in time
• Err(void) if the timeout fires

Timeout with error conversion

From demos/retry-on-error/run.ts:

withTimeout(constant(2_000), stepB.unwrapOr(throwError))
  .mapErr(constant("stepB: timed out"))
  .unwrapOr(throwError)
  .drop(),

1. withTimeout(constant(2_000), ...) — race stepB against a 2-second timer.
2. .mapErr(constant("stepB: timed out")) — replace the Err(void) with a descriptive string.
3. .unwrapOr(throwError) — on timeout, fire the enclosing tryCatch.

Dynamic timeout

The timeout duration doesn't have to be constant. It can come from the pipeline:

pipe(
  getConfig,                           // { timeout: 10000, ... }
  withTimeout(
    extractField("timeout"),           // extract the timeout from the config
    extractField("payload").then(work) // extract the payload and process it
  ),
)

How it works

withTimeout compiles to a race between the handler and a sleep. See algebraic effect handlers for the compilation details.