Effect escape hatches

Frond.Driver.Async is the default and covers most nodes — return a value or a Promise and you are done. Frond.Driver.Effect is the escape hatch: the same hooks, written in Effect. Reach for it when your code already lives in Effect, or when you want Effect’s structured concurrency, retries, and scheduling inside a hook.

The same driver, in Effect

import { Effect } from "effect";

driver: Frond.Driver.Effect<ProfileSpec>({
  acquire: Frond.Driver.Acquire((ctx) =>
    Effect.gen(function* () {
      const profile = yield* ctx.tryPromise((signal) =>
        fetch(`/api/profile/${ctx.args.userId}`, { signal }).then((r) => r.json())
      );
      return profile;
    })
  ),
}),

The hooks are identical to the async driver — acquire, refresh, release, live, actions — but each returns an Effect. On the Effect context, setResult, setResultValidity, and patchResult return Effects you yield*.

Bridging promises

ctx.tryPromise((signal) => run(signal)) lifts a promise into Effect and wires the abort signal for you, so cancellation propagates without extra plumbing.

yield* ctx.tryPromise((signal) => fetchWithRetry(url, { signal }));

In an async driver you would pass ctx.signal to fetch directly; tryPromise is the Effect equivalent.

When to reach for it

Use Async	Use Effect
Plain async/await or promises.	Code already written in Effect.
A single fetch or call.	Combining effects — concurrency, racing, retry schedules.
The common case.	You want Effect’s interruption and resource scoping inside the hook.

Effect drivers can require Effect services through the hook’s environment. Note that this applies to the driver only — a node’s key function must stay pure and may not use Effect services, time, or randomness. See Identity and keys.

Whichever you choose, the runtime treats the normalized driver identically: readiness, serialization, result validity, timeouts, cancellation, and cleanup do not change. The driver mode is an authoring choice, not a behavior change. See Drivers.

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Next: Public surface — the full export map.