Hope this is the right place to ask this, since th...

# functional

[Muhammad Talha]

Hope this is the right place to ask this, since this is like an Either type. I’m using the following sealed class to return success or error types (credit to https://phauer.com/2019/sealed-classes-exceptions-kotlin/). It’s working great. I can use the Outcome.Success class with a value. However is it possible to use it without a value? There are some cases where I don’t want to pass a value in. I’m not quite sure what the definition would be for me not to pass a value in while not making value optional. Thanks!

sealed class Outcome<out T: Any> {
    class Success<out T: Any>(val value: T) : Outcome<T>()
    class Error(val msg: String, val exp: Exception? = null) : Outcome<Nothing>()
}

[simon.vergauwen]

If you don't want to use a value then you should use Unit which means Success without a meaningful value.

In functional programming Either<Error, Unit> is typically used to signal that something can either fail with Error or succeed with no meaning value.

[simon.vergauwen]

You can also find all this in the https://arrow-kt.io/ library if you're not familiar with it.

Either for example can be found in Arrow Core. https://arrow-kt.io/docs/core/ and it offers nice DSLs for not requiring flatMap & map etc.

[Muhammad Talha]

Thanks! I’m new to Kotlin so I didn’t know about this library. I’ll check this out.

[simon.vergauwen]

My pleasure! If you have any questions there is an #arrow channel that is quite active.