Hi, I have an usecase, where I want to convert a list of entities to another entities. It is possibl...

# arrow

[Petr Laštovička]

Hi, I have an usecase, where I want to convert a list of entities to another entities. It is possible that this conversion results in an exception. If so I want to record the error, ignore the item and continue mapping. After the operation, I want to have a List of errors and a List of converted entities. I can think of using fold with two persistent list accumulators. Do you see a better way of doing something like this? Thanks

[simon.vergauwen]

Hey @Petr Laštovička,
You can use Either for this with seperateEither. https://arrow-kt.io/docs/apidocs/arrow-core/arrow.core/separate-either.html

Something like this:

fun convert(): Either<Throwable, Entity> =
  Either.catch { ... }

val (errors, entities) = list.map { convert() }
    .seperateEither()

[Petr Laštovička]

Very cool, thanks arrow

[simon.vergauwen]

My pleasure ☺️