# Cats Effect Resource > Scala resource lifecycle management with Cats Effect `Resource` and `IO`. Use when defining safe acquisition/release, composing resources (including parallel acquisition), or designing resource-safe APIs and cancellation behavior for files, streams, pools, clients, and background fibers. Use when this capability is needed. - Skill: `tomevault-io/cats-effect-resource` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/cats-effect-resource` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/cats-effect-resource/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/cats-effect-resource --- # Cats Effect Resource (Scala) ## Quick start - Model each resource with `Resource.make` or `Resource.fromAutoCloseable` and keep release idempotent. - Compose resources with `flatMap`, `mapN`, `parMapN`, or helper constructors; expose `Resource[F, A]` from APIs. - Use `Resource` at lifecycle boundaries and call `.use` only at the program edges. - Read `references/resource.md` for patterns, best practices, and API notes. ## Workflow 1. Identify acquisition, use, and release steps; decide if acquisition is blocking. 2. Implement a `Resource[F, A]` constructor using the smallest needed typeclass. 3. Compose resources into higher-level resources and keep finalizers minimal. 4. Decide how cancelation and errors should influence release logic. 5. Run with `.use` at the boundary (IOApp, service startup) and avoid leaking raw `A`. ## Usage guidance - Prefer `Resource` over `try/finally` or `bracket` when composition and cancelation safety matter. - Use `IO.blocking` (or `Sync[F].blocking`) for acquisition and release when calling blocking JVM APIs. - For background fibers, use `Resource` or `Supervisor` to ensure cleanup on cancelation. ## References - Load `references/resource.md` for API details, patterns, and examples. - For Kotlin/Arrow parallels, see the `arrow-resource` skill. - Install this skill with `npx skills add https://github.com/alexandru/skills --skill cats-effect-resource`. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/funfix) — claim your Tome and manage your conversions.