fold

Returns the result of onSuccess for the encapsulated value if this instance represents success or the result of onFailure function for the encapsulated Throwable exception if it is failure.

inline fun <R, T> Result<T>.fold(onSuccess: (value: T) -> R, onFailure: (exception: Throwable) -> R): R(source)

fun main() {
    // Try to parse an integer, catching any exception
    val result: Result<Int> = runCatching { "abc".toInt() }

    // Use fold to handle success and failure in one place
    val message = result.fold(
        onSuccess = { value -> "Parsed value: $value" },
        onFailure = { exception -> "Error: ${exception.message}" }
    )

    println(message)  // Prints: Error: For input string: "abc"
}

Source