I've opened the issue: https://github.com/IoLanguage/io/issues/460

My very uninformed feeling is it might have to do with some C "trickery" too advanced for GraalVM.

Thank you for your work and time.

Io is a beautiful language that I got interested in about the time I was learning Ruby (2004 perhaps).

Also, for a few years, your pages were the top sources of information on Objective C!

Thanks for all the work!