Either

Either

Intro

This is like an enum with two cases Success or Failure. Basically equivalent of result from swift or any other languagues.

code

import arrow.core.Either
import arrow.core.left
import arrow.core.right

fun process(input: Int): Either<String, String> {
    return if (input > 0) {
        "Success: $input".right()
    } else {
        "Error: Invalid input".left()
    }
}

fold

fun main() {
    val result1 = process(5)
    val unwrapped1 = result1.fold(
        { error -> "Operation failed: $error" },
        { success -> "Operation succeeded: $success" }
    )
    println(unwrapped1) // Output: Operation succeeded: Success: 5

    val result2 = process(-1)
    val unwrapped2 = result2.fold(
        { error -> "Operation failed: $error" },
        { success -> "Operation succeeded: $success" }
    )
    println(unwrapped2) // Output: Operation failed: Error: Invalid input
}

getOrElse

fun main() {
   val result1 = process(5)
    val unwrapped1 = result1.getOrElse { "Default value" }
    println(unwrapped1) // Output: Success: 5

    val result2 = process(-1)
    val unwrapped2 = result2.getOrElse { "Default value" }
    println(unwrapped2) // Output: Default value
}

when

fun main() {
    val result1 = process(5)
    when (result1) {
        is Either.Left -> println("Error occurred: ${result1.value}")
        is Either.Right -> println("Success: ${result1.value}")
    } // Output: Success: Success: 5

    val result2 = process(-1)
    when (result2) {
        is Either.Left -> println("Error occurred: ${result2.value}")
        is Either.Right -> println("Success: ${result2.value}")
    } // Output: Error occurred: Error: Invalid input
}

when (val result = secManagerDataSource.getDeviceIdentity()) {  
    is Either.Left -> assert(result.value.reason == 1)  
    is Either.Right -> {  
        val xact = result.value.xact  
        println(xact)  
        assert(xact.isNotBlank())  
    }  
}

AI

To unwrap an Either in Kotlin, several approaches can be used depending on the desired outcome and the context. The Either type, commonly provided by libraries like Arrow, represents a value that can be either a Left (typically used for errors) or a Right (typically used for success).

Using fold

The fold function allows you to handle both the Left and Right cases in a single expression.