[Solved] A bug in the Kotlin compiler caused issues with inline classes inside `crossinline suspend`...

# arrow

[Dario Valdespino]

[Solved] A bug in the Kotlin compiler caused issues with inline classes inside crossinline suspend functional parameters. Fixed in Kotlin 1.5.30-RC.
Is it a known bug that either {} does not work properly with value classes? For example, the following code:

@JvmInline
value class Metadata(val map: Map<String, String>)

fun reproduceBug() = either<Unit, Metadata>{
  Metadata(emptyMap())
}

Whenever I use debug to see the result of the function, it will contain a Right({}) , meaning that the right value actually contains the underlying Map instead of the Metadata wrapper. This causes a ClassCastException in runtime when using bind . Am I missing something?

[simon.vergauwen]

Hey @Dario Valdespino,

Yes, that’s exactly what is happening since the value class doesn’t exist at runtime. IIRC this bug is related to suspend + value class and is “unrelated” to the encoding inside either { }.

For this reason I’m currently not using value class yet in production (😞). So this is fixed in 1.5.30?

[Dario Valdespino]

Yep, I had to update to the 1.5.30-RC but it works as expected

[simon.vergauwen]

Cool, thanks for the update. That version should be released before we release Arrow 1.0.0 soon 🙂