counter.ts

export const make = Effect.struct({
  ref: SubscriptionRef.make(0),
});

export interface Counter extends Effect.Success<typeof make> {}
export const Counter = Tag<Counter>();
export const CounterLive = Layer.fromEffect(Counter)(make);

export const increment = Effect.serviceWithEffect(Counter, ({ ref }) =>
  ref.update((count) => count + 1)
);

export const decrement = Effect.serviceWithEffect(Counter, ({ ref }) =>
  ref.update((count) => count - 1)
);

export const subscribe = pipe(
  Effect.serviceWith(Counter, ({ ref }) => ref.changes),
  Stream.unwrap
);