A Result type representing either a success or a failure.

This is a Kotlin multi-platform library, supporting JVM, JS and major native targets. If you're a Kotlin JVM user, just add the following to the dependencies.

implementation("me.jason5lee:resukt:1.0.0")
implementation("me.jason5lee:resukt-jvm:1.0.0")

Unlike other result libraries, this library is implemented based on the one in the standard library, with the following opinionated designs.

• The failure type is a generic, so it is Result<T, F> instead of Result<T>.
• Use "failure" instead of "error" because "error" already has a meaning in JVM and Kotlin.
• The failure type isn't limited to be a Throwable. Actually I don't recommend defining failure as a Throwable. The failures of the logic are very different from the exceptions from the implementation and IO.
• Because of the reason above, the Throwable-related functions are put in the throwable package which I don't recommend to use.
• Provides andThen and whenFailure methods for easy error spreading in a multi-steps procedure. Check MultiStepsTest.kt for examples.
• Except the designs mentioned above, The implementation of this library is almost the same as the Result<T> in standard library.

For the people from pattern-matching or smart-casting languages: because it does not use the sealed class, it provides a fold method having the similar function of pattern-matching. It accepts two lambdas expression, one for the success case and another for failure case. For example, for a a: Result<Int, String>, you can do something like a.fold(onSuccess = { it / 2 }, onFailure = { println("Error: $it"); -1 }) .

Because Kotlin's standard library will be used if this Result is not imported, if you get a strange compile error, be sure you have me.jason5lee.resukt.Result or me.jason5lee.resukt.throwable.runCatching imported.

• Scott Wlaschin who showed me the idea of error modeling.
• michaelbull/kotlin-result for Gradle project and GitHub CI setup.