arrow-resource

name

arrow-resource

description

Kotlin + Arrow Resource lifecycle discipline with `Resource`, `ResourceScope`, `resourceScope`, and context parameters. Use for safe acquisition/release of files, streams, DB pools/connections, HTTP clients, background scopes, or multipart parts; preventing resource leaks and use-after-close bugs; designing companion `Resource` builders; using `arrow-autoclose` when only synchronous `AutoCloseable` cleanup is possible; composing resources with typed errors, cancellation, or parallel acquisition.

Arrow Resource (Kotlin)

Quick start

• Treat every disposable handle as scoped: wrap it in Resource and acquire it only inside resourceScope, resource {}, or Resource.use.
• Prefer arrow.fx.coroutines.resource.context imports for context-parameter-friendly resource, resourceScope, bind, install, and autoCloseable.
• Never return a disposable value from resourceScope { ... }, resource { ... }, or resource.use { ... }; that returns a closed handle.
• Classes must not allocate owned resources in ordinary constructors. Use a companion builder returning Resource<Class> or requiring context(ResourceScope).
• If suspend Resource cannot be used, use arrow-autoclose/AutoCloseable with the same no-leak discipline.
• Read references/resource.md before writing examples, reviews, or new APIs.

Workflow

1. Identify every owned disposable dependency and its release action.
2. Move acquisition into a Resource recipe or context(ResourceScope) builder.
3. Compose resources into higher-level resources with .bind() or context-parameter builders.
4. Keep resource handles private to the scoped object; expose operations, not the raw handle.
5. Execute at lifecycle boundaries with resourceScope/.use, and keep finalizers idempotent.

Usage guidance

• Prefer Resource over use/try/finally for suspend finalizers, cancellation awareness, composition, or multiplatform code.
• Use context parameters for scoped capabilities: context(_: ResourceScope) suspend fun acquire....
• Use ExitCase when release behavior depends on success, failure, or cancellation.
• Resource is FP-style ownership: acquisition and finalization are values/effects that compose; hidden side-effectful constructors are a design smell.
• When changing examples, update and run the bundled scripts/verify-examples.kt check.

References

• Load references/resource.md for rules, source links, and typechecked examples.