camelCaseVlad

На работе типизируем с флоу, может вам поможет, чем-то

// @flow
import { call, put, takeEvery } from 'redux-saga/effects';
import { setupSagaTarget } from '@work-util';
import { fetchApi } from './api';
import * as constants from '../constants'
import * as actions from '../actions';

/**
 * Fetch card data Saga
 * @returns {void}
 */
export function* fetchCData(): Iterator<*> {
  const data = yield call(fetchApi);
  if (data) {
    yield put(actions.success(data));
  }
}

export function* watchFetchRequest(): Iterator<*> {
  yield takeEvery(constants.APP_REQUEST, fetchData);
}

const sagas = [
  setupSagaTarget(watchFetchRequest, true, true),
];

export { sagas };

Использую Flow в проекте.

Фот как выглядит пример Апп редусера.

//@flow
import type {
  ActionWithPayloadType,
  AppStateType
} from '@project/types';
import { OPEN_MODAL, CLOSE_MODAL, SET_USER_LOGIN } from '../constants';

const initialState: AppStateType = {
  isModalOpen: false,
  isUserLoggedIn: false
};

//eslint-disable-next-line complexity
const appReducer = (
  state: AppStateType = initialState,
  action: ActionWithPayloadType = { type: '', payload: '' }
) : AppStateType => {

  if (!action) { return state; }

  if (action.type === OPEN_MODAL) {
    return { ...state, isModalOpen: true };
  }

  if (action.type === CLOSE_MODAL) {
    return { ...state, isModalOpen: false };
  }

  if (action.type === SET_USER_LOGIN) {
    return { ...state, isUserLoggedIn: action.payload };
  }

  return state;
};

export default appReducer;

@project/types

export type ActionWithPayloadType = {
  type: string,
  payload: *
};
export type AppStateType = {
  isModalOpen: boolean,
  isUserLoggedIn: boolean
}