MacRuby was an implementation of the Ruby language that ran on the Objective-C runtime and CoreFoundation framework under development by Apple Inc. which "was supposed to replace RubyCocoa". It targeted Ruby 1.9 and used the high performance LLVM compiler infrastructure starting with version 0.5. It supports both ahead-of-time and just-in-time compilation.MacRuby supported Interface Builder and shipped with a core library called HotCocoa to simplify Cocoa programming.