I have been trying out arrow. I have an interestin...

# arrow

[Arun Joseph]

I have been trying out arrow. I have an interesting situation with modelling errors, its not specific to arrow library.. Lets say I have two modules, account and savedroutes. The savedroutes module depends on account module.
account module has some failures

interface Failure {
    val errorMessage: String
}
/**
 * Describes the domain failures related to user account
 */
sealed interface UserAccountInfoFailure : Failure {
    /** No user info, no token */
    data class UnAuthenticated(
        override val errorMessage: String
    ) : UserAccountInfoFailure
...
}

savedroutes modules has some failures

/**
 * Describes the domain failures related to saving a route.
 */
sealed interface SaveRouteFailure : Failure {
    data class RouteTooLongFailure(
        override val errorMessage: String
    ) : SaveRouteFailure
   ...
}

I have a method in savedroutes which returns

fun getSavedRoutes(): Flow<Either<List<SavedRoute>, [SaveRouteFailure or UserAccountInfoFailure]>> {
    TODO()

I am trying to represent the fact that [SaveRouteFailure or UserAccountInfoFailure] as a single class, one idea I am trying is to create

sealed interface SaveRouteRepositoryFailure: Failure

and trying to make

sealed interface SaveRouteFailure : SaveRouteRepositoryFailure {

works

sealed interface UserAccountInfoFailure : SaveRouteRepositoryFailure {

which can't be done because account repository doesn't depend on savedroutes.
Have you had any experience in dealing with situations like above?

[mitch]

@Arun Joseph you can create a new type that unions the two..

sealed class GetSavedRouteFailure(override val errorMessage: String) : Failure {
  data class UserAccountFailure(val value: UserAccountInfoFailure) : GetSavedRouteFailure(value.errorMessage)
  data class SaveRouteFailure(val value: SavedRouteFailure) : GetSavedRouteFailure(value.errorMessage)
}

[Arun Joseph]

Thanks @mitch I will try this out.

[Tower Guidev2]

Im new to Arrow and FP in general
however I thought Either was right biased to have the Failure on Left and Success On Right,
@Arun Joseph if i am reading your definition correctly Either<List<SavedRoute>, [SaveRouteFailure or UserAccountInfoFailure]>, you have defined the opposite

[mitch]

and yeah it’s right biased, @Arun Joseph you should flip that List and Failure