actionMatcher.ts

import {Action} from '../actions/actionTypes';
import {isMatch} from 'lodash';

interface actionHandler {
  (action:Action, state:any):Object;
}

export class ActionMatcher {
  tests:Array<(action:Action) => boolean>;
  handler:actionHandler;

  constructor(type:string) {
    this.tests = [(action:Action) => action.type === type];
  }

  withMeta(metaShape:Object):ActionMatcher {
    this.tests.push((action:Action) => isMatch(action.meta, metaShape));
    return this;
  }
  isError():ActionMatcher {
    this.tests.push((action:Action) => action.error);
    return this;
  }
  then(handler:actionHandler):ActionMatcher {
    this.handler = handler;
    return this;
  }
  exec(action:Action, state:any):any {
    let nextState = state;
    const match = this.tests.reduce((agg, t) => agg && (t(action)), true);

    if (match) {
      nextState =  this.handler(action, state);
    }

    return nextState;
  }
}

export function extend (extension:{}) {
  Object.keys(extension).map((key) => {
    ActionMatcher.prototype[key] = extension[key];
  });
}


const matchAction = (type:string):ActionMatcher => {
  return new ActionMatcher(type);
}


export default matchAction;

actionTypes.ts

import {Dispatch} from 'redux';

export interface Action {
  type: string;
  error?:boolean;
  payload?:any;
  meta?:{};
}

interface ContainerActionMeta {
  field?:string,
  containerName: string;
}

export interface ContainerAction extends Action {
  meta: ContainerActionMeta;
}

loginScreenReducer.ts

const createReducer = (matchers:[ActionMatcher], initialState:any) => (state = initialState, action:Action) => {
  return matchers.reduce((s, matcher) => matcher.exec(action, s), state);
}

const updateField = (action:ContainerAction, state:any) => state.set(action.meta.field, action.payload);

export default createReducer([
  matchAction(UPDATE_CONTAINER_STATE)
    .withMeta({containerName: LOGIN_SCREEN, field: 'email'})
    .then(updateField),
    
  matchAction(UPDATE_CONTAINER_STATE)
    .withMeta({containerName: LOGIN_SCREEN, field: 'password'})
    .then(updateField),
    
  matchAction(LOGIN)
    .withMeta({phase: START})
    .then((action, state) => state.set('loading', true)),
    
  matchAction(LOGIN)
    .withMeta({phase: SUCCESS})
    .then((action, state) => state.set({'loggedIn': true, 'loading': false}),
    
  matchAction(LOGIN)
    .isError()
    .then((action, state) => state.set('errorMessage', action.payload))
], new LoginScreenStateRecord());

key bit is the bottom:

export default createReducer([
  matchAction(UPDATE_CONTAINER_STATE)
    .withMeta({containerName: LOGIN_SCREEN, field: 'email'})
    .then(updateField),

  matchAction(UPDATE_CONTAINER_STATE)
    .withMeta({containerName: LOGIN_SCREEN, field: 'password'})
    .then(updateField),

  matchAction(LOGIN)
    .withMeta({phase: START})
    .then((action, state) => state.set('loading', true)),

  matchAction(LOGIN)
    .withMeta({phase: SUCCESS})
    .then((action, state) => state.set({'loggedIn': true, 'loading': false}),

  matchAction(LOGIN)
    .isError()
    .then((action, state) => state.set('errorMessage', action.payload))
], new LoginScreenStateRecord());