Example action + reducer + lens + epic

campaigns.ts

/**
 * Get Campaigns
 */
export const getCampaigns = contactStrategyActionFactory.async<number, Campaign[], Error>('GET_CAMPAIGNS');
export const campaignsLens = Lens.fromProp<ContactStrategyStore, 'campaigns'>('campaigns');

const getCampaignsReducer = reducerFactory(getCampaigns, campaignsLens);
const getCampaignsEpic: Epic = a$ =>
  a$.pipe(
    filterSwitchAsync(getCampaigns, companyId => from(GetCampaigns({ companyId }).then(({ campaigns }) => campaigns)))
  );