Editing Ruby (programming language) (section)

=== Alternative implementations ===
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{{As of|2018}}, there are a number of alternative implementations of Ruby, including [[JRuby]], [[Rubinius]], and [[mruby]]. Each takes a different approach, with JRuby and Rubinius providing [[just-in-time compilation]] and mruby also providing [[ahead-of-time compilation]].

Ruby has three major alternative implementations:

* [[JRuby]], a mixed [[Java (programming language)|Java]] and Ruby implementation that runs on the [[Java virtual machine]]. JRuby currently targets Ruby 3.1.x.
* [[TruffleRuby]], a Java implementation using the Truffle language implementation framework with [[GraalVM]]
* [[Rubinius]], a [[C++]] bytecode virtual machine that uses [[LLVM]] to compile to machine code at runtime. The bytecode compiler and most core classes are written in pure Ruby. Rubinius currently{{when|date=April 2025}} targets Ruby 2.3.1.

Other Ruby implementations include:

* [[MagLev (software)|MagLev]], a [[Smalltalk]] implementation that runs on [[GemTalk Systems]]' [[Gemstone (database)|GemStone/S]] VM
* [[mruby]], an implementation designed to be embedded into C code, in a similar vein to [[Lua (programming language)|Lua]]. It is currently being developed by [[Yukihiro Matsumoto]] and others
* [[RGSS]], or Ruby Game Scripting System, a [[Proprietary software|proprietary]] implementation that is used by the [[RPG Maker]] series of software for game design and modification of the RPG Maker engine
* [[julializer]], a [[transpiler]] (partial) from Ruby to [[Julia (programming language)|Julia]]. It can be used for a large speedup over e.g. Ruby or JRuby implementations (may only be useful for numerical code).<ref name="virtual-module"/>
* [[Topaz (Ruby)|Topaz]], a Ruby implementation written in [[Python (programming language)|Python]]
* [[Opal (Ruby)|Opal]], a web-based interpreter that compiles Ruby to [[JavaScript]]

Other now defunct Ruby implementations were:
* [[MacRuby]], a [[macOS|Mac OS X]] implementation on the [[Objective-C]] runtime. Its iOS counterpart is called [[RubyMotion]]
* [[IronRuby]] an implementation on the [[.NET Framework]]
* Cardinal, an implementation for the [[Parrot virtual machine]]
* [[Ruby Enterprise Edition]], often shortened to ''ree'', an implementation optimized to handle large-scale [[Ruby on Rails]] projects
* [[HotRuby]], a [[JavaScript]] and [[ActionScript]] implementation of the [[Ruby programming language]]

The maturity of Ruby implementations tends to be measured by their ability to run the [[Ruby on Rails]] (Rails) framework, because it is complex to implement and uses many Ruby-specific features. The point when a particular implementation achieves this goal is called "the Rails singularity". The reference implementation, JRuby, and Rubinius<ref name="Rubinius"/> are all able to run Rails unmodified in a production environment.