Can I build, using Arrow, a custom, generic sum type similar to

Either

but with more subtypes? I need something like this:

sealed class DataState<T> {

    class Loading<T> : DataState<T>()

    data class Error<T>(val error: CallError) : DataState<T>()

    data class DataLoaded<T>(
        val data: T
    ) : DataState<T>()
}

And I want only the

DataLoaded

subtype to behave as

Either.Right

(e.g. when using

flatMap()

) and all other subtypes behave as

Either.Left

, i.e. having early returns from

flatMap()

. I especially would like to have the monad comprehension syntax analogous to the

either {}

DSL (using

.bind()

).

You can have the Left-y states have a common supertype, and then just use Either normally with Left being the supertype and Right being

DataLoaded

Thanks, that's a brilliant solution! I will try it out 🙏

Here is an example @Lukasz Kalnik, https://github.com/nomisRev/ktor-arrow-example/blob/main/src/main/kotlin/io/github/nomisrev/DomainError.kt I use

sealed interface

to define "layers", and then I can unite them with a common parent to closer they come to my API edge.

Thank you for the examples!