I have function that returns an `Either` ``` fu...

# arrow

[Hareendran]

I have function that returns an Either

fun getConfigVersion(configId: ConfigId, versionId: ConfigVersionId): Either<DomainError, PIConfigVersion> {
        val configVersion = configVersionRepository.findByPiConfigModel_ProfileIdAndVersion(configId.id, versionId.id)
        return configVersion?.right() ?: NoVersionsFound("No ConfigVersion found for Config ${configId.id} and version ${versionId.id}").left()
    }

[Ties]

.bind() is only available within an either { ... } block i believe

[Hareendran]

either.eager<DomainError, List<Policy>> {
                val piConfigVersion = getConfigVersion(evRequest.configId, evRequest.versionId).bind()
             
            }

[Hareendran]

is it something like this?

[raulraja]

hi @Hareendran yes, also a few more examples here https://arrow-kt.io/docs/patterns/error_handling/#either

[Hareendran]

Thank you @raulraja.. got it to work …

[Hareendran]

related q: how can I convert

List<Either<DomainError, Policy>>

[Hareendran]

to

Either<DomainError, List< Policy>>>

[Hareendran]

I had something like

results.sequence(Either.applicative()).fix().map { it.fix() }) {
            is Either.Left -> throw RuntimeException("There is an Error while saving incidents" + result.a)
            is Either.Right -> result.b
        }

[Hareendran]

but that doesn’t compile anymore with 1.0.1

[raulraja]

those no longer need an applicative constraint and they are specialized per data type

[raulraja]

https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/sequence.html

[raulraja]

there are also similar versions for traverse

[Hareendran]

I’m slightly confused by that statement.. so how do. we go from

List<Either<DomainError, Policy>>  to
Either<DomainError, List<Policy>>  to

[raulraja]

fun <E, A> Iterable<Either<E, A».sequenceEither(): Either<E, List<A»

[raulraja]

it would be in that case calling sequenceEither in the collection

[raulraja]

https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/traverse-either.html is the same but applying the identity function. If in addition to flipping the types you want to apply a transformation you would use traverseEither instead.

[raulraja]

Here is the specific versions of sequenceEither https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/sequence-either.html

[Hareendran]

Aha that is easier thank you