Actually, since this is Graal the Ruby implementation here is almost certainly https://github.com/oracle/truffleruby https://github.com/oracle/truffleruby so yo

Actually, since this is Graal the Ruby implementation here is almost certainly https://github.com/oracle/truffleruby https://github.com/oracle/truffleruby so you're invoking Ruby in the same compiler _and process space_ that underlies GraalJS (no transpilation to JS needed). That means the JVM can optimize calls between JS and Ruby (inlining JS values into Ruby method call sites, and vice versa).