Resource safety with acquireRelease, Effect.scoped, and finalizers. Use when opening files, sockets, servers, or external handles.
const withConn = Effect.acquireRelease(
Effect.sync(() => open()),
(conn) => Effect.sync(() => close(conn))
).pipe(Effect.flatMap(use))
yield* Effect.scoped(
Effect.gen(function* () {
const h = yield* Effect.acquireRelease(acquire(), release)
return yield* use(h)
})
)
yield* Effect.addFinalizer(() => cleanup)
operation.pipe(Effect.ensuring(cleanup))
const wrapS3Promise = <T>(promise: Promise<T> | Effect.Effect<Promise<T>>) =>
Effect.gen(function* () {
if (promise instanceof Promise) {
return yield* Effect.tryPromise({ try: () => promise, catch: (cause) => new S3Error({ cause }) })
}
return yield* promise.pipe(
Effect.flatMap((cb) =>
Effect.tryPromise({ try: () => cb, catch: (cause) => new S3Error({ cause }) })
)
)
}).pipe(Effect.catchTag("UnknownException", (cause) => new S3Error({ cause })))
// Usage with spans
const put = wrapS3Promise(client.send(new S3.PutObjectCommand(args))).pipe(
Effect.withSpan("S3.putObject", { attributes: { key: args.Key } })
)
CRITICAL: Search local Effect source before implementing
The full Effect source code is available at docs/effect-source/. Always search the actual implementation before writing Effect code.
docs/effect-source/effect/src/Effect.tsdocs/effect-source/effect/src/Scope.ts# Find acquireRelease patterns
grep -F "acquireRelease" docs/effect-source/effect/src/Effect.ts
# Study scoped operations
grep -F "scoped" docs/effect-source/effect/src/Effect.ts
grep -F "addFinalizer" docs/effect-source/effect/src/Effect.ts
# Find ensuring patterns
grep -F "ensuring" docs/effect-source/effect/src/Effect.ts
# Look at Scope implementation
grep -F "export" docs/effect-source/effect/src/Scope.ts | grep -F "function"
docs/effect-source/effect/src/Effect.ts for the implementationReal source code > documentation > assumptions