TypeScript + Reduxはもうぼちぼちサードライブラリに頼らなくてもある程度はいい感じに補完してくれる - Qiita

import { createStore, Reducer, Action, combineReducers, ActionCreatorsMapObject, ReducersMapObject, ActionCreator } from "redux" //// State全体の定義 export type AppState = { counter: number } //// ActionとActionCreatorの定義 // type CounterAction = Action<"INCREMENT" | "DECREMENT"> でも可 type CounterActionType = "INCREMENT" | "DECREMENT" type CounterAction = Action<CounterActionType> // これだけだるいが利用側のために二重定義し