effect with actionCreator

src/Updux.ts

@@ -311,8 +311,30 @@ export default class Updux<
         this.#defaultMutation = { mutation, terminal };
     }
 
-    addEffect(effect: EffectMiddleware) {
+    addEffect(actionCreator:
+        AggregateActions<ResolveActions<T_LocalActions>, T_Subduxes>,
+        effect: EffectMiddleware): EffectMiddleware;
+    addEffect(effect: EffectMiddleware): EffectMiddleware;
+    addEffect(...args) {
+        let effect;
+        if (args.length === 1) {
+            effect = args[0];
+        }
+        else {
+            const [actionCreator, originalEffect] = args;
+
+            effect = (api) => next => {
+                const e = originalEffect(api)(next);
+                return action => {
+                    const func = actionCreator.match(action) ? e : next;
+                    return func(action);
+                }
+            }
+        }
+
         this.#localEffects.push(effect);
+
+        return effect;
     }
 
     get effectsMiddleware() {

src/effects.test.ts

@@ -106,5 +106,30 @@ test('subdux', () => {
     expect(seen).toEqual(1);
 });
 
+test('addEffect with actionCreator', () => {
+    const dux = new Updux({
+        actions: {
+            foo: null,
+            bar: null,
+        },
+    });
+
+    const next = vi.fn();
+    const spy = vi.fn();
+
+    const mw = dux.addEffect(dux.actions.foo, (api) => (next) => (action) =>
+        next(spy(action))
+    );
+
+    mw({})(next)(dux.actions.bar());
+    expect(next).toHaveBeenCalled();
+    expect(spy).not.toHaveBeenCalled();
+
+    next.mockReset();
+    mw({})(next)(dux.actions.foo());
+    expect(next).toHaveBeenCalled();
+    expect(spy).toHaveBeenCalled();
+});
+
 // TODO subdux effects
 // TODO allow to subscribe / unsubscribe effects?