What return type should a Scala method have if it can throw/return errors but has Unit return type?

Question

So usually when we run a method that can both fail and return a value, we can encode our method return type as Either[SomeErrorType, ReturnType]. But many times

Answer 1

I use Try[Unit] for that case.

It encodes that the result of the method either succeeds or fails with some Exception, which can be further processed.

• vs T => Unit Try lifts errors to the application level, encoding in the signature that some error can be expected and allowing the application to handle it as a value.
• vs. Option[T] => Option is only able to encode that the operation had a value or not
• vs. Either[SomeErrorType, Unit] => Try It's easier to work with using monadic constructions.

I've used something like this to implement checks. (imaginary example)

for {
    entity <- receiveEntity // Try[Entity]
    _ <- isRelational(entity)
    _ <- isComplete(entity)
    _ <- isStable(entity)
} yield entity

where each check is of the form: Entity => Try[Unit]

This will return the entity if all checks pass of the first error that failed the check.