Replace Either with Throwing Exceptions

replaceEither.md

Replace Either with Throwing Exceptions

It is annoying to always unwrap a value from an Either only to be forced to handle the failure case.

Replace the Either value of the failure case with throwing an exception:

// ...
if (numberOfSeats > 1) {
  Right(makeReservation(numberOfSeats))
} else {
  Left(NotEnoughSeats)
}

// This is better because the caller is not forced to handle failure
if (numberOfSeats > 1) {
  makeReservation(numberOfSeats)
} else {
  throw new Exception("not enough seats")
}