Use do { } makes React render() method more readable

do notation.js

// FP languages permit to evaluate if/else expressions as values.
// In many cases it permits to avoid using mutable variables (var/let), multiple returns, or nested ternary operators

// This is the do { } notation (stage 0), that permits to write the following right now with Babel.

const Users = ({users}) =>   (
  <div>
    {users.map(user =>
      <UserCard key={user.id} user={user}/>
    )}
  </div>
)  

const UserList = ({users}) => do {
  if (!users) <div>Loading</div>
  else if (!users.length) <div>Empty</div>
  else <Users users={users}/>
}

can't wait pattern matching :D