effect-ts

Effect failures are returned as exits, not thrown, so try-catch inside Effect.gen does not catch them. Use Effect.catchTag or Effect.catchAll for recovery, Effect.result to inspect outcomes, and define typed errors with Data.TaggedError.

Define services with Context.Tag and provide implementations via Layer.succeed, or use Effect.Service to bundle a default implementation with dependencies and auto-generated accessors. Compose layers with Layer.merge and Layer.provide, then inject with Effect.provide.

Yes, the @prb/effect-next package provides typed helpers for Next.js 15+ route handlers, server actions, middleware, and React hooks. It also offers request-scoped caching via reactCache and a testing kit for asserting Effect results.

The @effect/vitest it.effect runner uses a TestClock where time does not pass automatically, so Effect.sleep stalls forever. Replace sleeps with TestClock.adjust, or switch the test to it.live when real wall-clock time is required.

The unsafeMake API may not exist in your installed Effect version, causing that runtime error. Use the safe SubscriptionRef.make constructor instead, which creates the reactive reference within an Effect and supports get, set, and changes.

Use Option<T> for internal Effect domain logic and T | null only at external boundaries like React props, JSON serialization, and API responses. Normalize at boundaries with Option.fromNullable on input and Option.getOrNull on output.