IRB is a REPL for Ruby which you can play with Ruby code.
IRB is also much improved: Added autocomplete and showing documents! pic.twitter.com/WWbLxNXWbY— 成瀬 (@nalsh) December 25, 2021
But if the color and cursor movements are too much for you, disable with
# ~/.irbrc IRB.conf[:USE_AUTOCOMPLETE] = false
You can also use
binding.irb in your app to interactively debug things (See Binding.
IRB 1.3.5 can paste multi-line with leading dots (ruby/irb #202).