/effect-ts

Runtime, Resources, and Concurrency

Resource Lifetimes

Acquire resources with Effect.acquireRelease or Effect.acquireUseRelease and run them in a Scope. Put long-lived clients and background processes in Layer.scoped; keep the Layer's Scope owned by the application runtime.

Every forked fiber needs an owner and a completion policy: join it, interrupt it, or place it in a Scope that closes. Do not create fire-and-forget fibers whose failures and finalizers become invisible.

Time and Scheduling

Use Effect Clock, Duration, and Schedule instead of ambient time and ad hoc timer loops. Duration inputs accept human-readable strings; preserve the project's established representation rather than normalizing for style alone.

Choose retry schedules from failure semantics: retry only transient failures, bound attempts or elapsed time, and keep non-retryable domain failures outside the retry predicate.

Coordination Primitives

• Ref owns mutable state accessed by Effects.
• Deferred is a one-shot synchronization or result handoff.
• SubscriptionRef owns state plus a stream of changes; construct it with the safe make API.

Do not reach for unsafe constructors merely to avoid yielding an Effect. For concurrency-sensitive behavior, test the coordination point explicitly rather than assuming a forked fiber has already run.