WIP
...

export class ActionCreator<T, P> {
  readonly type: T;
  readonly payload: P;

  constructor(type: T) { this.type = type; }
  create = (payload: P) => ({ type: this.type, payload });
}

// Example:
import { ActionCreator } from 'react-redux-typescript';

export const ActionCreators = {
  IncreaseCounter: new ActionCreator<'IncreaseCounter', number>('IncreaseCounter'),
  ChangeBaseCurrency: new ActionCreator<'ChangeBaseCurrency', string>('ChangeBaseCurrency'),
};

store.dispatch(ActionCreators.IncreaseCounter.create(4)); // { type: "IncreaseCounter", payload: 4 }
store.dispatch(ActionCreators.ChangeBaseCurrency.create('USD')); // { type: "ChangeBaseCurrency", payload: 'USD' }

// Action Types
type Action = typeof ActionCreators[keyof typeof ActionCreators];
// { type: "IncreaseCounter", payload: number } | { type: "ChangeBaseCurrency", payload: string }

// Reducer                                                           vvvvvv
export default function reducer(state: State = initialState, action: Action): State {
  if (action.type === ActionCreators.IncreaseCounter.type) {
    state.counter = action.payload; // number
  }
  else if (action.type === ActionCreators.ChangeBaseCurrency.type) {
    state.baseCurrency = action.payload; // string
  }
...

/**
 * @type EmptyAction - Empty Action Type
 * @template T - Generic Type
 */
export type EmptyAction<T> = {
  readonly type: T;
}

/**
 * @type PayloadAction - Flux Standard Action Type
 * @template T - Generic Type
 * @template P - Generic Type
 */
export type PayloadAction<T, P> = {
  readonly type: T;
  readonly payload: P;
  readonly error?: boolean;
}

export function createEmptyAction<T>(type: T): () => EmptyAction<T> {
  return () => ({ type });
};

export function createPayloadAction<T, P>(type: T): (payload: P) => PayloadAction<T, P> {
  return (payload) => ({ type, payload });
}

// returntypeof() - extract return type of an "expression"
// this polyfill exist because TypeScript does not support this feature yet 
// (tracking issue: https://github.com/Microsoft/TypeScript/issues/6606)
export function returntypeof<RT>(expression: (...params: any[]) => RT): RT {
  return {} as RT;
}

// Example:
import { returntypeof } from 'react-redux-typescript';

const mapStateToProps = (state: RootState) => ({
  counter: state.counter,
  baseCurrency: state.baseCurrency,
  currencies: CurrencyRatesSelectors.getCurrencies(state),
});

const dispatchToProps = {
  increaseCounter: ActionCreators.IncreaseCounter.create,
  changeBaseCurrency: ActionCreators.ChangeBaseCurrency.create,
};

// Props types inferred from mapStateToProps & dispatchToProps
const stateProps = returntypeof(mapStateToProps);
type Props = typeof stateProps & typeof dispatchToProps;
type State = {};

class CurrencyConverterContainer extends React.Component<Props, State> {
...
}

export default connect(mapStateToProps, dispatchToProps)(CurrencyConverterContainer);