IRB was written at 20 years ago and contains Ruby code parser by pure Ruby. The parser is contributing greatly to some Ruby tools over many years but the maintenance cost for new Ruby syntax continues to increase. IRB must parse Ruby code certainly for when should evaluate the code. I provide a solution for it. Ruby 1.9 or later has two big new features for this problem, Ripper and RubyVM::InstructionSequence.compile. The two features provide whether code piece continues by tokens information and syntax check.

After IRB implementation was modernized, I added some new features to IRB. IRB imports RDoc features as a library, such as show documentation with auto-complete, auto-complete for meta-programmed namespaces.