Resource Management (Scope)

Acquire/Release

const withConn = Effect.acquireRelease( Effect.sync(() => open()), (conn) => Effect.sync(() => close(conn)) ).pipe(Effect.flatMap(use))

Scoped

yield* Effect.scoped( Effect.gen(function* () { const h = yield* Effect.acquireRelease(acquire(), release) return yield* use(h) }) )

Finalizers

yield* Effect.addFinalizer(() => cleanup)

Ensuring

operation.pipe(Effect.ensuring(cleanup))

Real-world snippet: wrap Promise APIs with typed errors and spans

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 } }) )

Local Source Reference

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.

Key Source Files

• Effect: docs/effect-source/effect/src/Effect.ts

• Scope: docs/effect-source/effect/src/Scope.ts

Example Searches

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"

Workflow

• Identify the resource management API you need (e.g., acquireRelease)

• Search docs/effect-source/effect/src/Effect.ts for the implementation

• Study the types and resource patterns

• Look at test files for usage examples

• Write your code based on real implementations

Real source code > documentation > assumptions

References

• Agent Skills overview: https://www.anthropic.com/news/skills

• Skills guide: https://docs.claude.com/en/docs/claude-code/skills