feat(ts): use generic rest params with TS 3.0

package.json

@@ -32,7 +32,7 @@
     "nyc": "^12.0.2",
     "ts-node": "^7.0.0",
     "tslint": "^5.11.0",
-    "typescript": "^2.9.2"
+    "typescript": "^3.0.1"
   },
   "nyc": {
     "extension": [

src/actions.ts

@@ -17,36 +17,19 @@ export type ActionFunctionAny<R> = (...args: any[]) => R;
 
 export function createAction(
   type: string
-): ActionFunction0<IAction<undefined>>;
+): () => IAction<undefined>;
 
-export function createAction<Payload>(
+export function createAction<Payload, U extends any[]>(
   type: string,
-  payloadCreator: () => Payload
-): ActionFunction0<IAction<Payload>>;
+  payloadCreator: (...args: U) => Payload
+): (...args: U) => IAction<Payload>;
 
-export function createAction<Payload, Arg1>(
+export function createAction<Payload, U extends any[]>(
   type: string,
-  payloadCreator: ActionFunction1<Arg1, Payload>
-): ActionFunction1<Arg1, IAction<Payload>>;
-
-export function createAction<Payload, Arg1, Arg2>(
-  type: string,
-  payloadCreator: ActionFunction2<Arg1, Arg2, Payload>
-): ActionFunction2<Arg1, Arg2, IAction<Payload>>;
-
-export function createAction<Payload, Arg1, Arg2, Arg3>(
-  type: string,
-  payloadCreator: ActionFunction3<Arg1, Arg2, Arg3, Payload>
-): ActionFunction3<Arg1, Arg2, Arg3, IAction<Payload>>;
-
-export function createAction<Payload, Arg1, Arg2, Arg3, Arg4>(
-  type: string,
-  payloadCreator: ActionFunction4<Arg1, Arg2, Arg3, Arg4, Payload>
-): ActionFunction4<Arg1, Arg2, Arg3, Arg4, IAction<Payload>>;
-
-export function createAction<Payload>(type: string, payloadCreator?: (...args: any[]) => Payload) {
+  payloadCreator?: (...args: U) => Payload
+): (...args: U) => IAction<Payload> {
   return Object.assign(
-    (...args: any[]) => ({
+    (...args: U) => ({
       type,
       ...(payloadCreator && { payload: payloadCreator(...args) }),
     }),

test/actions.test.ts

@@ -11,16 +11,14 @@ describe('actions', () => {
   const TYPE = 'TEST_ACTION';
 
   describe('createAction', () => {
-    it('should create an action object with type', () => {
-      assert.equal(createAction(TYPE)().type, TYPE);
-    });
-
-    it('should create an action object with no payload', () => {
-      assert.equal(createAction(TYPE)().payload, undefined);
+    it('should create an action object with type and no payload', () => {
+      const action = createAction(TYPE);
+      assert.deepEqual(action(), { type: TYPE });
     });
 
     it('should output action name on toString()', () => {
-      assert.equal(createAction(TYPE).toString(), TYPE);
+      const action = createAction(TYPE);
+      assert.equal(action.toString(), TYPE);
     });
 
     it('should add the input to the payload', () => {