Ruby (programming language)

Early concept

According to Matsumoto, Ruby was conceived in 1993. In a 1999 post to the Ruby-Talk mailing list, he shared some of his early ideas about the language:^[9]

I was talking with my colleague about the possibility of an object-oriented scripting language. I knew Perl (Perl4, not Perl5), but I didn't like it really, because it had the smell of a toy language (it still has). The object-oriented language seemed very promising. I knew Python then. But I didn't like it, because I didn't think it was a true object-oriented language – OO features appeared to be add-on to the language. As a language maniac and OO fan for 15 years, I really wanted a genuine object-oriented, easy-to-use scripting language. I looked for but couldn't find one. So I decided to make it.

Matsumoto described Ruby's design as resembling a simple Lisp language at its core, with an object system like that of Smalltalk, blocks inspired by higher-order functions, and practical utility like that of Perl.^[10]

The name "Ruby" originated during an online chat session between Matsumoto and Keiju Ishitsuka on 24 February 1993, before any code had been written.^[11] Two names were initially proposed: "Coral" and "Ruby". Matsumoto chose the latter in a subsequent email to Ishitsuka.^[12] He also noted that one factor influencing the choice of the name was that a colleague's birthstone was ruby.^[13][14]

Early releases

The first public release of Ruby 0.95 was announced on Japanese domestic newsgroups on 21 December 1995.^[15][16] Subsequently, three more versions of Ruby were released in two days.^[11] The release coincided with the launch of the Japanese-language ruby-list mailing list, which was the first mailing list for the new language.

Already present at this stage of development were many of the features familiar in later releases of Ruby, including object-oriented design, classes with inheritance, mixins, iterators, closures, exception handling and garbage collection.^[17]

After the release of Ruby 0.95 in 1995, several stable versions of Ruby were released in these years.^[11]

In 1997, the first article about Ruby was published on the Web. In the same year, Matsumoto was hired by netlab.jp to work on Ruby as a full-time developer.^[11]

In 1998, the Ruby Application Archive was launched by Matsumoto, along with a simple English-language homepage for Ruby.^[11]

In 1999, the first English language mailing list ruby-talk began, which signaled a growing interest in the language outside Japan.^[18] In this same year, Matsumoto and Keiju Ishitsuka wrote the first book on Ruby, The Object-oriented Scripting Language Ruby (オブジェクト指向スクリプト言語 Ruby), which was published in Japan in October 1999. It would be followed in the early 2000s by around 20 books on Ruby published in Japanese.^[11]

By 2000, Ruby was more popular than Python in Japan.^[19] In September 2000, the first English language book Programming Ruby was printed, which was later freely released to the public, further widening the adoption of Ruby amongst English speakers. In early 2002, the English-language ruby-talk mailing list was receiving more messages than the Japanese-language ruby-list, demonstrating Ruby's increasing popularity in the non-Japanese speaking world.

Ruby 1.8 and 1.9

Ruby 1.8 was initially released in August 2003, was stable for a long time, and was retired in June 2013.^[20] Although deprecated, there is still code based on it. Ruby 1.8 is only partially compatible with Ruby 1.9.^{[citation needed]}

Ruby 1.8 has been the subject of several industry standards. The language specifications for Ruby were developed by the Open Standards Promotion Center of the Information-Technology Promotion Agency (a Japanese government agency) for submission to the Japanese Industrial Standards Committee (JISC) and then to the International Organization for Standardization (ISO). It was accepted as a Japanese Industrial Standard (JIS X 3017) in 2011^[21] and an international standard (ISO/IEC 30170) in 2012.^[22][23]

Around 2005, interest in the Ruby language surged in tandem with Ruby on Rails, a web framework written in Ruby. Rails is frequently credited with increasing awareness of Ruby.^[24]

Effective with Ruby 1.9.3, released 31 October 2011,^[25] Ruby switched from being dual-licensed under the Ruby License and the GPL to being dual-licensed under the Ruby License and the two-clause BSD license.^[26] Adoption of 1.9 was slowed by changes from 1.8 that required many popular third party gems to be rewritten.^{[citation needed]}

Ruby 2

Ruby 2.0 was intended to be fully backward compatible with Ruby 1.9.3. As of the official 2.0.0 release on 24 February 2013, there were only five known incompatibilities.^[27]

Starting with 2.1.0, Ruby's versioning policy changed to be more similar to semantic versioning, although it differs slightly in that minor version increments may be API incompatible.^[28]

Ruby 2.2.0 includes speed-ups, bugfixes, and library updates and removes some deprecated APIs. Most notably, Ruby 2.2.0 introduces changes to memory handling – an incremental garbage collector, support for garbage collection of symbols and the option to compile directly against jemalloc. It also contains experimental support for using vfork(2) with system() and spawn(), and added support for the Unicode 7.0 specification. Since version 2.2.1,^[29] Ruby MRI performance on PowerPC64 was improved.^[30][31][32] Features that were made obsolete or removed include callcc, the DL library, Digest::HMAC, lib/rational.rb, lib/complex.rb, GServer, Logger::Application as well as various C API functions.^[33]

Ruby 2.3.0 includes many performance improvements, updates, and bugfixes including changes to Proc#call, Socket and IO use of exception keywords, Thread#name handling, default passive Net::FTP connections, and Rake being removed from stdlib.^[34] Other notable changes include:

• The ability to mark all string literals as frozen by default with a consequently large performance increase in string operations.^[35]
• Hash comparison to allow direct checking of key/value pairs instead of just keys.
• A new safe navigation operator &. that can ease nil handling (e.g. instead of if obj && obj.foo && obj.foo.bar, we can use if obj&.foo&.bar).
• The did_you_mean gem is now bundled by default and required on startup to automatically suggest similar name matches on a NameError or NoMethodError.
• Hash#dig and Array#dig to easily extract deeply nested values (e.g. given profile = { social: { wikipedia: { name: 'Foo Baz' } } }, the value Foo Baz can now be retrieved by profile.dig(:social, :wikipedia, :name)).
• .grep_v(regexp) which will match all negative examples of a given regular expression in addition to other new features.

Ruby 2.4.0 includes performance improvements to hash table, Array#max, Array#min, and instance variable access.^[36] Other notable changes include:

• Binding#irb: Start a REPL session similar to binding.pry
• Unify Fixnum and Bignum into Integer class
• String supports Unicode case mappings, not just ASCII
• A new method, Regexp#match?, which is a faster Boolean version of Regexp#match
• Thread deadlock detection now shows threads with their backtrace and dependency

A few notable changes in Ruby 2.5.0 include rescue and ensure statements automatically use a surrounding do-end block (less need for extra begin-end blocks), method-chaining with yield_self, support for branch coverage and method coverage measurement, and easier Hash transformations with Hash#slice and Hash#transform_keys On top of that come a lot of performance improvements like faster block passing (3 times faster), faster Mutexes, faster ERB templates and improvements on some concatenation methods.

A few notable changes in Ruby 2.6.0 include an experimental just-in-time compiler (JIT), and RubyVM::AbstractSyntaxTree (experimental).

A few notable changes in Ruby 2.7.0 include pattern Matching (experimental), REPL improvements, a compaction GC, and separation of positional and keyword arguments.

Ruby 3

Ruby 3.0.0 was released on Christmas Day in 2020.^[37] It is known as Ruby 3x3, which signifies that programs would run three times faster in Ruby 3.0 comparing to Ruby 2.0.^[38] and some had already been implemented in intermediate releases on the road from 2 to 3. To achieve 3x3, Ruby 3 comes with MJIT, and later YJIT, Just-In-Time Compilers, to make programs faster, although they are described as experimental and remain disabled by default (enabled by flags at runtime).

Another goal of Ruby 3.0 is to improve concurrency and two more utilities Fibre Scheduler, and experimental Ractor facilitate the goal.^[37] Ractor is light-weight and thread-safe as it is achieved by exchanging messages rather than shared objects.

Ruby 3.0 introduces RBS language to describe the types of Ruby programs for static analysis.^[37] It is separated from general Ruby programs.

There are some syntax enhancements and library changes in Ruby 3.0 as well.^[37]

Ruby 3.1 was released on 25 December 2021.^[39] It includes YJIT, a new, experimental, Just-In-Time Compiler developed by Shopify, to enhance the performance of real world business applications. A new debugger is also included. There are some syntax enhancements and other improvements in this release. Network libraries for FTP, SMTP, IMAP, and POP are moved from default gems to bundled gems.^[40]

Ruby 3.2 was released on 25 December 2022.^[41] It brings support for being run inside of a WebAssembly environment via a WASI interface. Regular expressions also receives some improvements, including a faster, memoized matching algorithm to protect against certain ReDoS attacks, and configurable timeouts for regular expression matching. Additional debugging and syntax features are also included in this release, which include syntax suggestion, as well as error highlighting. The MJIT compiler has been re-implemented as a standard library module, while the YJIT, a Rust-based JIT compiler now supports more architectures on Linux.

Ruby 3.3 was released on 25 December 2023.^[42] Ruby 3.3 introduces significant enhancements and performance improvements to the language. Key features include the introduction of the Prism parser for portable and maintainable parsing, the addition of the pure-Ruby JIT compiler RJIT, and major performance boosts in the YJIT compiler. Additionally, improvements in memory usage, the introduction of an M:N thread scheduler, and updates to the standard library contribute to a more efficient and developer-friendly Ruby ecosystem.

Ruby 3.4 was released on 25 December 2024.^[43] Ruby 3.4 adds it block parameter reference, changes Prism as default parser, adds Happy Eyeballs Version 2 support to socket library, improves YJIT, adds modular Garbage Collector and so on.^[44]

Ruby 4

Ruby 4.0 was released 25 December 2025.^[45] It adds experimental ZJIT, a JIT written in Rust, and experimental "Ruby Box", a feature to provide separation about definitions. It was decided to bump the version number to 4.0 instead of 3.5 to celebrate Ruby's 30th birthday.^[46]

Matz's Ruby interpreter

The original Ruby interpreter is often referred to as Matz's Ruby Interpreter or MRI. This implementation is written in C and uses its own Ruby-specific virtual machine.

The standardized and retired Ruby 1.8 implementation was written in C, as a single-pass interpreted language.^[20]

Starting with Ruby 1.9, and continuing with Ruby 2.x and above, the official Ruby interpreter has been YARV ("Yet Another Ruby VM"), and this implementation has superseded the slower virtual machine used in previous releases of MRI.

Alternative implementations

As of 2026^[update], 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 and Ruby implementation that runs on the Java virtual machine. JRuby currently targets Ruby 3.4.
• 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 targets Ruby 2.3.1.

Other Ruby implementations include:

• MagLev, a Smalltalk implementation that runs on GemTalk Systems' GemStone/S VM
• mruby, an implementation designed to be embedded into C code, in a similar vein to Lua. It is being developed by Yukihiro Matsumoto and others
• RGSS, or Ruby Game Scripting System, a proprietary implementation used by the RPG Maker series of role-playing game creation software for game design and modification of the RPG Maker game engine
• julializer, a transpiler (partial) from Ruby to Julia. It can be used for a large speedup over e.g. Ruby or JRuby implementations (may only be useful for numerical code).^[63]
• Topaz, a Ruby implementation written in Python
• Opal, a web-based interpreter that compiles Ruby to JavaScript

Other now defunct Ruby implementations were:

• MacRuby, a 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^[64] are all able to run Rails unmodified in a production environment.

Platform support

Matsumoto originally developed Ruby on the 4.3BSD-based Sony NEWS-OS 3.x, but later migrated his work to SunOS 4.x, and finally to Linux.^[65][66] By 1999, Ruby was known to work across many different operating systems. Modern Ruby versions and implementations are available on all major desktop, mobile and server-based operating systems. Ruby is also supported across a number of cloud hosting platforms like Jelastic, Heroku, Google Cloud Platform and others.

Tools such as RVM and RBEnv, facilitate installation and partitioning of multiple ruby versions, and multiple 'gemsets' on one machine.

Strings and Symbols

Ruby has multiple string types which can cause problems. Both are garbage collected since Ruby 2.2.^[70] Before Ruby 2.2 creating lots of symbols would just leak memory.^[71]

• Symbols are identical to Lua-strings which are immutable, hashed and only exist once in memory with many references to it and thus quick to compare.
• Strings on the other hand are a separate object each time they occur in the program with their own mutable data storage that is not hashed and thus quick to create and manipulate.
• Strings come in many encodings. Strings of different encodings are also incompatible and throw an error when joined. in `join': incompatible character encodings: UTF-8 and ASCII-8BIT (Encoding::CompatibilityError). This can happen easily because many functions return strings as ASCII-8BIT by default.^[72] The programmer has to manually set the encoding of the string with .force_encoding(Encoding::UTF_8) when such strings are encountered. The character encodings UTF-8 and ASCII-8BIT are not actually incompatible and usually both contain UTF-8. Throwing an error creates a lot more bugs than it prevents.

However having multiple string types creates problems. Among others that associative arrays (Hash) in Ruby have separate indices for "strings" and :symbols of the same value and "a" is not equal to :a requiring conversion between types.

{:a=>"one", "a"=>"two"}[:a]
# one
{:a=>"one", "a"=>"two"}["a"]
# two
:a != "a"
# true

Significant whitespace

Just like Python, Ruby is a language with significant whitespace, which can cause subtle bugs if users aren't aware of where it belongs and where it doesn't.^[73]

foo = 23
def bar
  42
end
puts bar/foo
# 1

foo = 23
def bar
  42
end
puts bar /foo
# unterminated regexp meets end of file

This can even cause different results without error:

def square(n)
  n * n
end

result_a = square(3 + 3) * 2
puts result_a # Output: 72  (36 * 2)

result_b = square (3 + 3) * 2
puts result_b # Output: 144 (square(12))

Multiple comparison operators

Like C and C++ (C alternative tokens) Ruby has alternative comparison operators: and alongside && and or alongside ||. However their behavior is vastly different which confuses all newcomers.^[74][75] and and or have lower precedence than assignments and function calls.

result = false || true
# result is true
result = false or true
# result is false but line evaluated to true