Result variant of Either pattern

result.kt

sealed class Result <out V, out E> {
  
    // Idle state
    object Loading : Result<Nothing, Nothing>()

    // Operation finished correctly with result saved on value
    data class Ok <out V > constructor (val value: V): Result<V, Nothing>()
  
    // Operation finished with error
    data class Err <out E> constructor (val error: E): Result<Nothing, E>() 
}