A modern programming language that makes developers happier.

kotlinlang

I think the easier explanation is that why would you ever code in terms of concrete `ArrayList` if you have the abstraction `List`. In the same way why would you code to `Either` if you have `ApplicativeError`. In addition Either is a sync data type and only suitable for your use case if it's all sync or you are already forcing async boundaries outside of Arrow control via coroutines or similar. Either can't suspend side effects