Attempt to chain Kotlin's Result

test.kt

private fun first(a: Int): Result<Int?> =
    when(a % 2 == 0) {
        true -> Result.success(value = a)
        false -> Result.failure(Exception("$a is odd"))
    }

private fun second(a: Int?): Result<Int?> = Result.failure(Exception("Because!"))

private fun third(a: Int?): Result<Int?> =
    when(a?.compareTo(10)) {
        0 -> Result.success(value = a)
        else -> Result.failure(Exception("$a is too big"))
    }

@Test
fun `It chains monads`() {
    var out = first(a = 2).map { firstOutput -> second(a = firstOutput) }.map { secondOutput -> third(a = secondOutput.getOrNull()) }.map { firstOutput -> second(a = firstOutput.getOrNull()) }
    if (out.isSuccess) {
        println("YO!")
        println(out.getOrNull())
    } else {
        println(out)
        println("Nah...")
        println(out.getOrNull())
    }
}

test_2.kt

# with https://github.com/michaelbull/kotlin-result#chaining

private fun uno(a: Int): com.github.michaelbull.result.Result<Int, String> =
    when(a % 2 == 0) {
        true -> Ok(value = a)
        false -> Err("$a is odd")
    }

private fun due(a: Int): com.github.michaelbull.result.Result<Int, String> =
    when(a < 10) {
        true -> Ok(value = a)
        false -> Err("$a is too big")
    }

@Test
fun `Chain Eithers`() {
    var out_1 = uno(a = 40).andThen(::due)
    when(out_1) {
        is Ok -> println(out_1.get())
        is Err -> println(out_1.getError())
    }

    var out_2 = uno(a = 4).andThen(::due)
    when(out_2) {
        is Ok -> println(out_2.get())
        is Err -> println(out_2.getError())
    }
}