/effect-ts

Effect Atom

Effect Atom separates core atoms from framework bindings. Verify APIs against the installed packages:

• core constructors, Registry, Result, RPC, and HTTP integrations: @effect-atom/atom/*;
• React hooks and Registry provider: @effect-atom/atom-react.

import * as Atom from "@effect-atom/atom/Atom";
import * as Result from "@effect-atom/atom/Result";
import { RegistryProvider, useAtomSet, useAtomValue } from "@effect-atom/atom-react";

Atom Semantics

• Atom.make(value) creates writable state; Atom.make(get => value) creates derived state.
• An Effect or Stream passed to Atom.make produces a Result, not the raw success value.
• Use Atom.family for stable parameterized atoms and Atom.keepAlive only when state must outlive component mounts.
• Use Atom.runtime(layer) when atoms need an Effect runtime with services.
• Atom.fn creates a writable Effect/Stream function. Its handler receives the written argument and atom context.
• Use get.addFinalizer or a scoped Effect for listeners and resources owned by an atom.

React Boundaries

Use useAtomValue to read and useAtomSet to write. For Effect-backed mutation atoms, select mode: "promiseExit" when the caller must branch on typed success or failure; do not throw away the Exit merely to mimic an untyped async callback.

Render Result states explicitly, including initial/waiting and failure. Use suspense hooks only when the surrounding React boundary is designed to suspend or surface failures.

Inspect AtomRpc, AtomHttpApi, and hydration modules only when the task uses them; do not load their APIs for ordinary state work.