Rails is not written in Ruby | solnic.codes

This brings us to Ruby - a programming language with open classes, where even the core functionality of the language can be extended by simply adding new methods to core classes, like String or Array. This makes it very simple to create your own Ruby dialect!This unique feature of Ruby has been leveraged by DHH back when he created Ruby on Rails framework. The very foundation of this framework is a library called ActiveSupport - a big collection of core Ruby extensions, which together create a Ruby dialect, an extended version of the Ruby language, which doesn’t change it’s intrinsic nature. Why is it a foundation of the framework, you may ask - the answer is very simple: everything would break if you tried to remove ActiveSupport from Rails.