- Unify Fixnum and Bignum into Integer
- String supports Unicode case mappings
- Array#max, Array#min
- Introduce hash table improvement
- Regexp#match?
- Thread#report_on_exception and Thread.report_on_exception
- Thread deadlock detection now shows threads with their backtrace and dependency
- Binding#irb: Start a REPL session similar to
binding.pry - Performance improvements
What’s new in Ruby 2.4?
