back-end-fp-memoized-funcs.js

const getUserFromDatabase = memoize(async ctx => {
  const {
    req: {
      headers: {Authorization: userCred},
    },
  } = ctx;
  const user = await db.getUserByCredential(userCred);
  return user;
});

const sendMessageToUser = memoize(async ctx => {
  const {username} = await getUserFromDatabase(ctx);
  await messaging.sendToUser(username, 'hello');
});

const replyOk = memoize(async ctx => {
  const {username} = await getUserFromDatabase(ctx);
  const {res} = ctx;
  res.status(200).send('done');
});