Kotlin Multiplatform Result Class

Wrapper for kotlin.Result with KMM goodness, s.t. it becomes possible to expose a result class to public APIs interfacing with platform-specific code. For Kotlin/Native (read: iOS), this requires a Result equivalent, which is not a value class (a sealed Either type also does not interop well with Swift).

KmmResult comes to the rescue! →Full documentation.

Using in your Projects

This library is available at maven central.

Gradle

dependencies {
    api("at.asitplus:kmmresult:$version")   //This library was designed to play well with multiplatform APIs
}                                           //and is therefore intended to be exposed through your public API

Quick Start

Creation of Success and Failure objects is provided through a companion:

var intResult = KmmResult.success(3)
intResult = KmmResult.failure (NotImplementedError("Not Implemented"))

Also provides map() to transform success types while passing through errors and mapFailure to transform error types while passing through success cases. In addition, the more generic fold() is available for conveniently operating on both success and failure branches.

There really is not much more to say, except for two things:

• KmmResult sports unwrap() to conveniently map it to the kotlin.Result equivalent
• It provides a Result.wrap() extension function to go the opposite way.

Refer to the full documentation for more info.

Java

Works from the JVM as expected:

KmmResult<Boolean> demonstrate() {
    if (new Random().nextBoolean())
        return KmmResult.failure(new NotImplementedError("Not Implemented"));
    else
        return KmmResult.success(true);
}

Swift

Use the initializers:

func funWithKotlin() -> KmmResult<NSString> {
    if 2 != 3 {
        return KmmResult(failure: KotlinThrowable(message: "error!"))
    } else {
        return KmmResult(value: "works!")
    }
}

Happy folding!