https://github.com/piotrwitek/typesafe-actions/issues/22

actions.ts

import { buildAction } from 'typesafe-actions';

export const authActions = {
  getLoggedUser: buildAction('GET_LOGGED_USER').empty(),
  fetchAuth: buildAction('AUTH').async<
    {
      pending: boolean
      email: string,
      password: string
    },
    {
      pending: boolean,
      logged: boolean,
      token: string,
      refreshToken: string,
      email: string,
      username: string,
      id: string,
    },
    {
      show: boolean,
      type: string,
      message: string
    }
    >()
};

reducer.ts

import { getType } from 'typesafe-actions';
import { RootAction } from './root-action';
import { authActions } from './actions';

export type AuthState = Readonly<{
  pending: boolean,
  logged: boolean,
  token: string,
  refreshToken: string,
  email: string,
  username: string,
  id: string,
  alert: {
    show: boolean,
    type: string,
    message: string
  }
}>

const initialState: AuthState = {
  pending: true,
  logged: false,
  token: '',
  refreshToken: '',
  email: '',
  username: '',
  id: '',
  alert: {
    show: false,
    type: '',
    message: ''
  }
};

export const authReducer = (state: AuthState = initialState, action: RootAction) => {
  switch (action.type) {
    case getType(authActions.getLoggedUser):
      return Object.assign({}, state, {
        pending: false
      });
    case getType(authActions.fetchAuth.request):
      return Object.assign({}, state, {
        pending: action.payload.pending
      });
    default:
      return state
  }
};

root-action.ts

import { ActionsUnion } from 'typesafe-actions';
import { authActions } from './actions'

const actions = {
  ...authActions
};

export type RootAction = ActionsUnion<typeof actions>;