I implemented "Reline" that is a compatibility library with "readline" stdlib by pure Ruby and works correctly without GNU Readline and works on Windows too.

"Reidline" is authored for new IRB by keiju-san who is Ruby's grandfather, it behaves as a multiline editor like JavaScript console on browsers. It had many technical problems but I've already solved that when I implemented Reline. So I helped to complete Reidline.

These are highlights of Ruby 2.7. I'll talk about the technical problems of these and show a demo on Ruby 2.7.