Enhances error handling with a custom `Result` type, allowing flexible error types and eliminating the need for wrapping results in Ok/Error objects, streamlining code efficiency.
This is a little library that provides an improved way to use Result in Kotlin, with custom error types and also a way to avoid wrapping result objects into Ok and Error wrapper objects.
Why
There are two cool ways, in Kotlin standard library, to handle errors: kotlin.Result and sealed classes; though both present some limitations.
The standard Result uses exceptions as error type, which means you can't specify the type of possible error values.
With sealed classes you can define the set of both errors and ok values, but you lose the general flexibility and expressiveness of Result by using functions such as map, mapError, , etc.
This library
This library aims to provide the best of both worlds, by providing a Result type that can be used with any type of error,
and a set of extension functions to make it easier to work with it.
Furthermore, it provides two additional interfaces, ItsOk and ItsError which allow you to avoid wrapping results into and objects, for cleaner and more efficient code.
Both the error and ok types can be a single class or multiple classes that all inherit from and , especially useful to define in a sealed interface or sealed class.
See the example below to understand how it works.
import io.paoloconte.itsok.*
sealedinterfaceRepositoryError: ItsError<RepositoryError> {
object NotFound : RepositoryError
dataclassInvalidInput(val message: String) : RepositoryError
}
dataclassUser(val name: String, val age: Int): ItsOk<User>
funfindUser(id: Int): Result<User, RepositoryError> {
returnif (id == 1)
User("Mario", 30) // no need to wrap in Okelse
RepositoryError.NotFound // no need to wrap in Error
}
funmain() {
val result = findUser(1)
.map { user ->
user.name
}
.getOrElse {
println("User not found")
return
}
println("User name is -> $result")
}
