I teach Intro CS in Kotlin in the fall and like to start students with the REPL, which I was able to...

# intellij

[Ellen Spertus]

I teach Intro CS in Kotlin in the fall and like to start students with the REPL, which I was able to get working in 2022 and 2023 but not this year. Specifically, I installed IntelliJ IDEA 2024.1.4 (Ultimate Edition) with OpenJDK 21.0.1, created a project with the IntelliJ build system, and added a short file Conversation.kt. When I open the REPL, rebuild the application, and try calling it, I get the error:

error: class 'ConversationKt' is compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler
converse()

I found this 2022 bug report. Any suggestions?

[hfhbd]

What happens when you use 2024.2 RC?

[Ellen Spertus]

@hfhbd I haven't tried that. Is there a reason to think that would work? I prefer to steer my novice students to full releases rather than RCs.

I'm updating to 2024.1.6 now.

[hfhbd]

Maybe because the Kotlin plugin uses 2.0.0 and K2 and 2024.2 supports full K2, but didn’t check it.

[Klitos Kyriacou]

The REPL uses whatever version of Kotlin comes with IntelliJ. Check KotlinVersion.CURRENT. I've got IntelliJ IDEA 2024.2 (which has recently been fully released) and it uses Kotlin 1.9.24. You'll need to compile your projects with a version of Kotlin that's not later than 1.9.

[Klitos Kyriacou]

Having said that, I find the REPL a bit hard to use (it is still marked as experimental) but I find it much nicer to use a Kotlin scratch file instead (menu: New -> Scratch File).

[Ellen Spertus]

Thank you. I was planning to use Kotlin 2, but 1.9 is fine.

[Ellen Spertus]

Thanks for those tips! I was able to get the REPL working by changing the compiler version to 1.9.0, but I like the scratch file, which I hadn't tried before.