Ruby (programming language)

Last updated
Ruby logo.svg
Paradigm Multi-paradigm: functional, imperative, object-oriented, reflective
Designed by Yukihiro Matsumoto
Developer Yukihiro Matsumoto, et al.
First appeared1995;26 years ago (1995)
Stable release
3.0.1 [1]   OOjs UI icon edit-ltr-progressive.svg / 5 April 2021;2 months ago (5 April 2021)
Typing discipline Duck, dynamic, strong
Scope Lexical, sometimes dynamic
Implementation language C
OS Cross-platform
License Ruby License, GPLv2, or 2-clause BSD license [2] [3] [4]
Filename extensions .rb
Major implementations
Ruby MRI, YARV, Rubinius, MagLev, JRuby, MacRuby, RubyMotion, Mruby, IronRuby
Influenced by
Ada, [5] Basic, [6] C++, [5] CLU, [7] Dylan, [7] Eiffel, [5] Lisp, [7] Lua, Perl, [7] Python, [7] Smalltalk [7]
Clojure, CoffeeScript, Crystal, D, Elixir, Groovy, Ioke, [8] Julia, [9] Mirah, Nu, [10] Ring, [11] Rust, [12] Swift [13]

Ruby is an interpreted, high-level, general-purpose programming language. It was designed and developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan.


Ruby is dynamically typed and uses garbage collection and just-in-time compilation. It supports multiple programming paradigms, including procedural, object-oriented, and functional programming. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, BASIC, and Lisp. [14] [15]


Early concept

Matsumoto has said that Ruby was conceived in 1993. In a 1999 post to the ruby-talk mailing list, he describes some of his early ideas about the language: [16]

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 describes the design of Ruby as being like 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. [17]

The name "Ruby"

The name "Ruby" originated during an online chat session between Matsumoto and Keiju Ishitsuka on February 24, 1993, before any code had been written for the language. [18] Initially two names were proposed: "Coral" and "Ruby". Matsumoto chose the latter in a later e-mail to Ishitsuka. [19] Matsumoto later noted a factor in choosing the name "Ruby" – it was the birthstone of one of his colleagues. [20] [21]

First publication

The first public release of Ruby 0.95 was announced on Japanese domestic newsgroups on December 21, 1995. [22] [23] Subsequently, three more versions of Ruby were released in two days. [18] 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. [24]

Early releases

Following the release of Ruby 0.95 in 1995, several stable versions of Ruby were released in the following years:

In 1997, the first article about Ruby was published on the Web. In the same year, Matsumoto was hired by to work on Ruby as a full-time developer. [18]

In 1998, the Ruby Application Archive was launched by Matsumoto, along with a simple English-language homepage for Ruby. [18]

In 1999, the first English language mailing list ruby-talk began, which signaled a growing interest in the language outside Japan. [25] 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. [18]

By 2000, Ruby was more popular than Python in Japan. [26] 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

Ruby 1.8 was initially released August 2003, was stable for a long time, and was retired June 2013. [27] Although deprecated, there is still code based on it. Ruby 1.8 is only partially compatible with Ruby 1.9.

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 [28] and an international standard (ISO/IEC 30170) in 2012. [29] [30]

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. [31]

Ruby 1.9

Ruby 1.9 was released on Christmas Day in 2007. Effective with Ruby 1.9.3, released October 31, 2011, [32] 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. [33] Adoption of 1.9 was slowed by changes from 1.8 that required many popular third party gems to be rewritten.

Ruby 1.9 introduces many significant changes over the 1.8 series. [34] Examples:

Ruby 1.9 has been obsolete since February 23, 2015, [35] and it will no longer receive bug and security fixes. Users are advised to upgrade to a more recent version.

Ruby 2.0

Ruby 2.0 added several new features, including:

Ruby 2.0 was intended to be fully backward compatible with Ruby 1.9.3. As of the official 2.0.0 release on February 24, 2013, there were only five known (minor) incompatibilities. [37]

Ruby 2.0 has been obsolete since February 24, 2016, [38] and it will no longer receive bug and security fixes. Users are advised to upgrade to a more recent version.

Ruby 2.1

Ruby 2.1.0 was released on Christmas Day in 2013. [39] The release includes speed-ups, bugfixes, and library updates.

Starting with 2.1.0, Ruby's versioning policy is more like semantic versioning. [40] Although similar, Ruby's versioning policy is not compatible with semantic versioning:

RubySemantic versioning
MAJOR: Increased when incompatible change which can't be released in MINOR. Reserved for special events.MAJOR: Increased when you make incompatible API changes.
MINOR: increased every Christmas, may be API incompatible.MINOR: increased when you add functionality in a backwards-compatible manner.
TEENY: security or bug fix which maintains API compatibility. May be increased more than 10 (such as 2.1.11), and will be released every 2–3 months.PATCH: increased when you make backwards-compatible bug fixes.
PATCH: number of commits since last MINOR release (will be reset at 0 when releasing MINOR).-

Semantic versioning also provides additional labels for pre-release and build metadata are available as extensions to the MAJOR.MINOR.PATCH format, not available at Ruby.

Ruby 2.1 has been obsolete since April 1, 2017, [41] and it will no longer receive bug and security fixes. Users are advised to upgrade to a more recent version.

Ruby 2.2

Ruby 2.2.0 was released on Christmas Day in 2014. [42] The release 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.

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. [43]

Ruby 2.2 has been obsolete since April 1, 2018, [44] and it will no longer receive bug and security fixes. Users are advised to upgrade to a more recent version.

PowerPC64 performance
Since version 2.2.1, [45] Ruby MRI performance on PowerPC64 was improved. [46] [47] [48]

Ruby 2.3

Ruby 2.3.0 was released on Christmas Day in 2015. A few notable changes include:

The 2.3 branch also 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. [50]

Ruby 2.4

Ruby 2.4.0 was released on Christmas Day in 2016. A few notable changes include:

The 2.4 branch also includes performance improvements to hash table, Array#max, Array#min, and instance variable access. [51]

Ruby 2.5

Ruby 2.5.0 was released on Christmas Day in 2017. [52] A few notable changes include:

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.

Ruby 2.6

Ruby 2.6.0 was released on Christmas Day in 2018. [53] A few notable changes include:

Ruby 2.7

Ruby 2.7.0 was released on Christmas Day in 2019. [54] A few notable changes include:

Ruby 3.0

Ruby 3.0.0 was released on Christmas Day in 2020. [55] It is known as Ruby 3x3. One of its main aims was to switch the interpreter to a Just-In-Time Compiler, to make programs faster.

Table of versions

VersionLatest teeny versionInitial release dateEnd of support phaseEnd of security maintenance phase
Old version, no longer maintained: 1.0NA1996-12-25 [56] NANA
Old version, no longer maintained: [57] 2003-08-04 [58] 2012-06 [59] 2014-07-01 [60]
Old version, no longer maintained: [61] 2007-12-25 [62] 2014-02-23 [63] 2015-02-23 [64]
Old version, no longer maintained: [65] 2013-02-24 [66] 2015-02-24 [65] 2016-02-24 [65]
Old version, no longer maintained: [67] 2013-12-25 [68] 2016-03-30 [69] [70] 2017-03-31 [71] [72]
Old version, no longer maintained: [73] 2014-12-25 [74] 2017-03-28 [75] 2018-03-31 [72]
Old version, no longer maintained: [76] 2015-12-25 [77] 2018-06-20 [78] 2019-03-31 [78]
Old version, no longer maintained: [79] 2016-12-25 [80] 2019-04-01 [81] 2020-04-01 [81]
Old version, no longer maintained: [82] 2017-12-25 [83] 2021-04-05 [82] 2021-04-05 [82]
Older version, yet still maintained: [84] 2018-12-25 [85] 2021-04-05 [84] 2022-04-05 [84]
Older version, yet still maintained: [86] 2019-12-25 [87] TBATBA
Current stable version: [88] 2020-12-25 [89] TBATBA
Old version
Older version, still maintained
Latest version
Latest preview version
Future release


Yukihiro Matsumoto, the creator of Ruby Yukihiro Matsumoto.JPG
Yukihiro Matsumoto, the creator of Ruby

Matsumoto has said that Ruby is designed for programmer productivity and fun, following the principles of good user interface design. [90] At a Google Tech Talk in 2008 Matsumoto further stated, "I hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language." [91] He stresses that systems design needs to emphasize human, rather than computer, needs: [92]

Often people, especially computer engineers, focus on the machines. They think, "By doing this, the machine will run fast. By doing this, the machine will run more effectively. By doing this, the machine will something something something." They are focusing on machines. But in fact we need to focus on humans, on how humans care about doing programming or operating the application of the machines. We are the masters. They are the slaves.

Ruby is said to follow the principle of least astonishment (POLA), meaning that the language should behave in such a way as to minimize confusion for experienced users. Matsumoto has said his primary design goal was to make a language that he himself enjoyed using, by minimizing programmer work and possible confusion. He has said that he had not applied the principle of least astonishment to the design of Ruby, [92] but nevertheless the phrase has come to be closely associated with the Ruby programming language. The phrase has itself been a source of surprise, as novice users may take it to mean that Ruby's behaviors try to closely match behaviors familiar from other languages. In a May 2005 discussion on the newsgroup comp.lang.ruby, Matsumoto attempted to distance Ruby from POLA, explaining that because any design choice will be surprising to someone, he uses a personal standard in evaluating surprise. If that personal standard remains consistent, there would be few surprises for those familiar with the standard. [93]

Matsumoto defined it this way in an interview: [92]

Everyone has an individual background. Someone may come from Python, someone else may come from Perl, and they may be surprised by different aspects of the language. Then they come up to me and say, 'I was surprised by this feature of the language, so Ruby violates the principle of least surprise.' Wait. Wait. The principle of least surprise is not for you only. The principle of least surprise means principle of least my surprise. And it means the principle of least surprise after you learn Ruby very well. For example, I was a C++ programmer before I started designing Ruby. I programmed in C++ exclusively for two or three years. And after two years of C++ programming, it still surprises me.



Ruby is object-oriented: every value is an object, including classes and instances of types that many other languages designate as primitives (such as integers, booleans, and "null"). Variables always hold references to objects. Every function is a method and methods are always called on an object. Methods defined at the top level scope become methods of the Object class. Since this class is an ancestor of every other class, such methods can be called on any object. They are also visible in all scopes, effectively serving as "global" procedures. Ruby supports inheritance with dynamic dispatch, mixins and singleton methods (belonging to, and defined for, a single instance rather than being defined on the class). Though Ruby does not support multiple inheritance, classes can import modules as mixins.

Ruby has been described as a multi-paradigm programming language: it allows procedural programming (defining functions/variables outside classes makes them part of the root, 'self' Object), with object orientation (everything is an object) or functional programming (it has anonymous functions, closures, and continuations; statements all have values, and functions return the last evaluation). It has support for introspection, reflection and metaprogramming, as well as support for interpreter-based [101] threads. Ruby features dynamic typing, and supports parametric polymorphism.

According to the Ruby FAQ, the syntax is similar to Perl and the semantics are similar to Smalltalk, but it differs greatly from Python. [102]


The syntax of Ruby is broadly similar to that of Perl and Python. Class and method definitions are signaled by keywords, whereas code blocks can be defined by either keywords or braces. In contrast to Perl, variables are not obligatorily prefixed with a sigil. When used, the sigil changes the semantics of scope of the variable. For practical purposes there is no distinction between expressions and statements. [103] [104] Line breaks are significant and taken as the end of a statement; a semicolon may be equivalently used. Unlike Python, indentation is not significant.

One of the differences from Python and Perl is that Ruby keeps all of its instance variables completely private to the class and only exposes them through accessor methods (attr_writer, attr_reader, etc.). Unlike the "getter" and "setter" methods of other languages like C++ or Java, accessor methods in Ruby can be created with a single line of code via metaprogramming; however, accessor methods can also be created in the traditional fashion of C++ and Java. As invocation of these methods does not require the use of parentheses, it is trivial to change an instance variable into a full function, without modifying a single line of calling code or having to do any refactoring achieving similar functionality to C# and VB.NET property members.

Python's property descriptors are similar, but come with a trade-off in the development process. If one begins in Python by using a publicly exposed instance variable, and later changes the implementation to use a private instance variable exposed through a property descriptor, code internal to the class may need to be adjusted to use the private variable rather than the public property. Ruby's design forces all instance variables to be private, but also provides a simple way to declare set and get methods. This is in keeping with the idea that in Ruby, one never directly accesses the internal members of a class from outside the class; rather, one passes a message to the class and receives a response.

See the Examples section below for samples of code demonstrating Ruby syntax.


The Ruby official distribution also includes irb, an interactive command-line interpreter that can be used to test code quickly. The following code fragment represents a sample session using irb:

$ irbirb(main):001:0> puts'Hello, World'Hello, World => nilirb(main):002:0> 1+2 => 3


The following examples can be run in a Ruby shell such as Interactive Ruby Shell, or saved in a file and run from the command line by typing ruby <filename>.

Classic Hello world example:

puts'Hello World!'

Some basic Ruby code:

# Everything, including a literal, is an object, so this works:-199.abs# => 199'ice is nice'.length# => 11'ruby is cool.'.index('u')# => 1"Nice Day Isn't It?".downcase.split('').uniq.sort.join# => " '?acdeinsty"


print'Please type name >'name=gets.chompputs"Hello #{name}."


puts'Give me a number'number=gets.chompputsnumber.to_ioutput_number=number.to_i+1putsoutput_number.to_s+' is a bigger number.'


There are a variety of ways to define strings in Ruby.

The following assignments are equivalent:

a="\nThis is a double-quoted string\n"a=%Q{\nThis is a double-quoted string\n}a=%{\nThis is a double-quoted string\n}a=%/\nThis is a double-quoted string\n/a=<<-BLOCKThis is a double-quoted stringBLOCK

Strings support variable interpolation:

var=3.14159"pi is #{var}"=>"pi is 3.14159"

The following assignments are equivalent and produce raw strings:

a='This is a single-quoted string'a=%q{This is a single-quoted string}


Constructing and using an array:

a=[3,'hello',14.5,1,2,[6,15]]a[2]# => 14.5a.[](2)# => 14.5a.reverse# => [[6, 15], 2, 1, 14.5, 'hello', 3]a.flatten.uniq# => [3, 'hello', 14.5, 1, 2, 6, 15]

Constructing and using an associative array (in Ruby, called a hash): equivalent to hash = {}hash={water:'wet',fire:'hot'}# makes the previous line redundant as we are now# assigning hash to a new, separate hash objectputshash[:fire]# prints "hot"hash.each_pairdo|key,value|# or: hash.each do |key, value|puts"#{key} is #{value}"end# returns {:water=>"wet", :fire=>"hot"} and prints:# water is wet# fire is hothash.delete:water# deletes the pair :water => 'wet' and returns "wet"hash.delete_if{|key,value|value=='hot'}# deletes the pair :fire => 'hot' and returns {}

Control structures

If statement:

# Generate a random number and print whether it's even or odd.ifrand(100).even?puts"It's even"elseputs"It's odd"end

Blocks and iterators

The two syntaxes for creating a code block:

{puts'Hello, World!'}# note the braces# or:doputs'Hello, World!'end

A code block can be passed to a method as an optional block argument. Many built-in methods have such arguments:'file.txt','w')do|file|# 'w' denotes "write mode"file.puts'Wrote some text.'end# file is automatically closed hereFile.readlines('file.txt').eachdo|line|putslineend# => Wrote some text.

Parameter-passing a block to be a closure:

# In an object instance variable (denoted with '@'), remember a block.defremember(&a_block)@block=a_blockend# Invoke the preceding method, giving it a block that takes a name.remember{|name|puts"Hello, #{name}!"}# Call the closure (note that this happens not to close over any free variables)'Jon')# => "Hello, Jon!"

Creating an anonymous function:

proc{|arg|putsarg}{|arg|putsarg}lambda{|arg|putsarg}->(arg){putsarg}# introduced in Ruby 1.9

Returning closures from a method:

defcreate_set_and_get(initial_value=0)# note the default value of 0closure_value=initial_value[{|x|closure_value=x},{closure_value}]endsetter,getter=create_set_and_get# returns two => 21# Parameter variables can also be used as a binding for the closure,# so the preceding can be rewritten as:defcreate_set_and_get(closure_value=0)[proc{|x|closure_value=x},proc{closure_value}]end

Yielding the flow of program control to a block that was provided at calling time:

defuse_helloyield"hello"end# Invoke the preceding method, passing it a block.use_hello{|string|putsstring}# => 'hello'

Iterating over enumerations and arrays using blocks:

array=[1,'hi',3.14]array.each{|item|putsitem}# prints:# 1# 'hi'# 3.14array.each_index{|index|puts"#{index}: #{array[index]}"}# prints:# 0: 1# 1: 'hi'# 2: 3.14# The following uses a (a..b) Range(3..6).each{|num|putsnum}# prints:# 3# 4# 5# 6# The following uses a (a...b) Range(3...6).each{|num|putsnum}# prints:# 3# 4# 5

A method such as inject can accept both a parameter and a block. The inject method iterates over each member of a list, performing some function on it while retaining an aggregate. This is analogous to the foldl function in functional programming languages. For example:

[1,3,5].inject(10){|sum,element|sum+element}# => 19

On the first pass, the block receives 10 (the argument to inject) as sum, and 1 (the first element of the array) as element. This returns 11, which then becomes sum on the next pass. It is added to 3 to get 14, which is then added to 5 on the third pass, to finally return 19.

Using an enumeration and a block to square the numbers 1 to 10 (using a range):

(1..10).collect{|x|x*x}# => [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

Or invoke a method on each item (map is a synonym for collect):

(1..5).map(&:to_f)# => [1.0, 2.0, 3.0, 4.0, 5.0]


The following code defines a class named Person. In addition to initialize, the usual constructor to create new objects, it has two methods: one to override the <=> comparison operator (so Array#sort can sort by age) and the other to override the to_s method (so Kernel#puts can format its output). Here, attr_reader is an example of metaprogramming in Ruby: attr_accessor defines getter and setter methods of instance variables, but attr_reader only getter methods. The last evaluated statement in a method is its return value, allowing the omission of an explicit return statement.

classPersonattr_reader:name,:agedefinitialize(name,age)@name,@age=name,ageenddef<=>(person)# the comparison operator for sorting@age<=>person.ageenddefto_s"#{@name} (#{@age})"endendgroup=["Bob",33),"Chris",16),"Ash",23)]putsgroup.sort.reverse

The preceding code prints three names in reverse age order:

Bob (33) Ash (23) Chris (16) 

Person is a constant and is a reference to a Class object.

Open classes

In Ruby, classes are never closed: methods can always be added to an existing class. This applies to all classes, including the standard, built-in classes. All that is needed to do is open up a class definition for an existing class, and the new contents specified will be added to the existing contents. A simple example of adding a new method to the standard library's Time class:

# re-open Ruby's Time => 2013-09-03 16:09:37 +0300yesterday=today.yesterday# => 2013-09-02 16:09:37 +0300

Adding methods to previously defined classes is often called monkey-patching. If performed recklessly, the practice can lead to both behavior collisions with subsequent unexpected results and code scalability problems.

Since Ruby 2.0 it has been possible to use refinements to reduce the potentially negative consequences of monkey-patching, by limiting the scope of the patch to particular areas of the code base.

# re-open Ruby's Time classmoduleRelativeTimeExtensionsrefineTimedodefhalf_a_day_agoself-43200endendendmoduleMyModuleclassMyClass# Allow the refinement to be


An exception is raised with a raise call:


An optional message can be added to the exception:

raise"This is a message"

Exceptions can also be specified by the programmer:

raiseArgumentError,"Illegal arguments!"

Alternatively, an exception instance can be passed to the raise method:"Illegal arguments!")

This last construct is useful when raising an instance of a custom exception class featuring a constructor that takes more than one argument:

classParseError<Exceptiondefinitialize(input,line,pos)super"Could not parse '#{input}' at line #{line}, position #{pos}""Foo",3,9)

Exceptions are handled by the rescue clause. Such a clause can catch exceptions that inherit from StandardError. Other flow control keywords that can be used when handling exceptions are else and ensure:

begin# do somethingrescue# handle exceptionelse# do this if no exception was raisedensure# do this whether or not an exception was raisedend

It is a common mistake to attempt to catch all exceptions with a simple rescue clause. To catch all exceptions one must write:

begin# do somethingrescueException# Exception handling code here.# Don't write only "rescue"; that only catches StandardError, a subclass of Exception.end

Or catch particular exceptions:

begin# do somethingrescueRuntimeError# handle only RuntimeError and its subclassesend

It is also possible to specify that the exception object be made available to the handler clause:

begin# do somethingrescueRuntimeError=>e# handling, possibly involving e, such as "puts e.to_s"end

Alternatively, the most recent exception is stored in the magic global $!.

Several exceptions can also be caught:

begin# do somethingrescueRuntimeError,Timeout::Error=>e# handling, possibly involving eend


Ruby code can programmatically modify, at runtime, aspects of its own structure that would be fixed in more rigid languages, such as class and method definitions. This sort of metaprogramming can be used to write more concise code and effectively extend the language.

For example, the following Ruby code generates new methods for the built-in String class, based on a list of colors. The methods wrap the contents of the string with an HTML tag styled with the respective color.

COLORS={black:"000",red:"f00",green:"0f0",yellow:"ff0",blue:"00f",magenta:"f0f",cyan:"0ff",white:"fff"}classStringCOLORS.eachdo|color,code|define_method"in_#{color}"do"<span style=\"color: ##{code}\">#{self}</span>"endendend

The generated methods could then be used like this:

"Hello, World!".in_blue=>"<span style=\"color: #00f\">Hello, World!</span>"

To implement the equivalent in many other languages, the programmer would have to write each method (in_black, in_red, in_green, etc.) separately.

Some other possible uses for Ruby metaprogramming include:


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. [27]

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.

Alternate implementations

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 alternate implementations:

Other Ruby implementations include:

Other now defunct Ruby implementations were:

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 [106] are all able to run Rails unmodified in a production environment.

Platform support

Matsumoto originally did Ruby development on the 4.3BSD-based Sony NEWS-OS 3.x, but later migrated his work to SunOS 4.x, and finally to Linux. [107] [108]

By 1999, Ruby was known to work across many different operating systems, including NEWS-OS, SunOS, AIX, SVR4, Solaris, NEC UP-UX, NeXTSTEP, BSD, Linux, Mac OS, DOS, Windows, and BeOS. [109]

Modern Ruby versions and implementations are available on many operating systems, such as Linux, BSD, Solaris, AIX, macOS, Windows, Windows Phone, [110] Windows CE, Symbian OS, BeOS, and IBM i.

Ruby programming language is supported across a number of cloud hosting platforms like Jelastic, Heroku, Google Cloud Platform and others.

Repositories and libraries

RubyGems is Ruby's package manager. A Ruby package is called a "gem" and can be installed via the command line. Most gems are libraries, though a few exist that are applications, such as IDEs. [111] There are over 10,000 Ruby gems hosted on

Many new and existing Ruby libraries are hosted on GitHub, a service that offers version control repository hosting for Git.

The Ruby Application Archive, which hosted applications, documentation, and libraries for Ruby programming, was maintained until 2013, when its function was transferred to RubyGems. [112]

See also

Related Research Articles

Common Lisp (CL) is a dialect of the Lisp programming language, published in ANSI standard document ANSI INCITS 226-1994 (S20018). The Common Lisp HyperSpec, a hyperlinked HTML version, has been derived from the ANSI Common Lisp standard.

Eiffel is an object-oriented programming language designed by Bertrand Meyer and Eiffel Software. Meyer conceived the language in 1985 with the goal of increasing the reliability of commercial software development; the first version becoming available in 1986. In 2005, Eiffel became an ISO-standardized language.

Smalltalk Object-oriented programming language first released in 1972

Smalltalk is an object-oriented, dynamically typed reflective programming language. Smalltalk was created as the language underpinning the "new world" of computing exemplified by "human–computer symbiosis". It was designed and created in part for educational use, specifically for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan Kay, Dan Ingalls, Adele Goldberg, Ted Kaehler, Diana Merry, Scott Wallace, and others during the 1970s.

Lua (programming language) Lightweight programming language

Lua is a lightweight, high-level, multi-paradigm programming language designed primarily for embedded use in applications. Lua is cross-platform, since the interpreter of compiled bytecode is written in ANSI C, and Lua has a relatively simple C API to embed it into applications.

In computer science, reflective programming or reflection is the ability of a process to examine, introspect, and modify its own structure and behavior.

Apache Groovy Programming language

Apache Groovy is a Java-syntax-compatible object-oriented programming language for the Java platform. It is both a static and dynamic language with features similar to those of Python, Ruby, and Smalltalk. It can be used as both a programming language and a scripting language for the Java Platform, is compiled to Java virtual machine (JVM) bytecode, and interoperates seamlessly with other Java code and libraries. Groovy uses a curly-bracket syntax similar to Java's. Groovy supports closures, multiline strings, and expressions embedded in strings. Much of Groovy's power lies in its AST transformations, triggered through annotations.

In some programming languages, eval, short for the English evaluate, is a function which evaluates a string as though it were an expression and returns a result; in others, it executes multiple lines of code as though they had been included instead of the line including the eval. The input to eval is not necessarily a string; it may be structured representation of code, such as an abstract syntax tree, or of special type such as code. The analog for a statement is exec, which executes a string as if it were a statement; in some languages, such as Python, both are present, while in other languages only one of either eval or exec is.

This article compares two programming languages: C# with Java. While the focus of this article is mainly the languages and their features, such a comparison will necessarily also consider some features of platforms and libraries. For a more detailed comparison of the platforms, please see Comparison of the Java and .NET platforms.

Java syntax

The syntax of Java refers to the set of rules defining how a Java program is written and interpreted.

In computer programming, an entry point is a point in a program where the execution of a program begins, and where the program has access to command line arguments.

In computer programming languages, a switch statement is a type of selection control mechanism used to allow the value of a variable or expression to change the control flow of program execution via search and map.

Harbour is a computer programming language, primarily used to create database/business programs. It is a modernized, open sourced and cross-platform version of the older Clipper system, which in turn developed from the dBase database market of the 1980s and 1990s.

C Sharp (programming language) Multi-paradigm (object-oriented) programming language

C# is a general-purpose, multi-paradigm programming language encompassing static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines.

Scala (programming language) General-purpose programming language

Scala is a strong statically typed general-purpose programming language which supports both object-oriented programming and functional programming. Designed to be concise, many of Scala's design decisions are aimed to address criticisms of Java.

eRuby is a templating system that embeds Ruby into a text document. It is often used to embed Ruby code in an HTML document, similar to ASP, JSP and PHP and other server-side scripting languages. The templating system of eRuby combines the ruby code and the plain text to provide flow control and variable substitution, thus making it easy to maintain.

GNU Smalltalk

GNU Smalltalk is an implementation of the Smalltalk programming language by the GNU Project.

A symbol in computer programming is a primitive data type whose instances have a unique human-readable form. Symbols can be used as identifiers. In some programming languages, they are called atoms. Uniqueness is enforced by holding them in a symbol table. The most common use of symbols by programmers is for performing language reflection, and most common indirectly is their use to create object linkages.

The structure of the Perl programming language encompasses both the syntactical rules of the language and the general ways in which programs are organized. Perl's design philosophy is expressed in the commonly cited motto "there's more than one way to do it". As a multi-paradigm, dynamically typed language, Perl allows a great degree of flexibility in program design. Perl also encourages modularization; this has been attributed to the component-based design structure of its Unix roots, and is responsible for the size of the CPAN archive, a community-maintained repository of more than 100,000 modules.

Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTSTEP operating system. Objective-C was the standard programming language supported by Apple for developing macOS and iOS applications using their respective application programming interfaces (APIs), Cocoa and Cocoa Touch, until the introduction of Swift in 2014.

Crystal (programming language)

Crystal is a general-purpose, object-oriented programming language, designed and developed by Ary Borenszweig, Juan Wajnerman, Brian Cardiff and more than 300 contributors. With syntax inspired by the language Ruby, it is a compiled language with static type-checking, but specifying the types of variables or method arguments is generally unneeded. Types are resolved by an advanced global type inference algorithm. Crystal is currently in active development. It is released as free and open-source software under the Apache License version 2.0.


  2. "[ruby] Contents of /trunk/COPYING" . Retrieved 2 May 2015.
  3. "[ruby] Contents of /trunk/GPL" . Retrieved 2 May 2015.
  4. "[ruby] Contents of /trunk/BSDL" . Retrieved 2 May 2015.
  5. 1 2 3 Cooper, Peter (2009). Beginning Ruby: From Novice to Professional. Beginning from Novice to Professional (2nd ed.). Berkeley: APress. p. 101. ISBN   978-1-4302-2363-4. To a lesser extent, Python, LISP, Eiffel, Ada, and C++ have also influenced Ruby.
  6. "Confreaks TV | Reasons behind Ruby - Ruby Conference 2008". Retrieved 2019-06-25.
  7. 1 2 3 4 5 6 Bini, Ola (2007). Practical JRuby on Rails Web 2.0 Projects: Bringing Ruby on Rails to Java. Berkeley: APress. p.  3. ISBN   978-1-59059-881-8. It draws primarily on features from Perl, Smalltalk, Python, Lisp, Dylan, and CLU.
  8. Bini, Ola. "Ioke". Archived from the original on 2011-07-21. Retrieved 2011-07-21. inspired by Io, Smalltalk, Lisp and Ruby
  9. "Julia 1.0 Documentation: Introduction" . Retrieved 6 October 2018.
  10. Burks, Tim. "About Nu™". Programming Nu™. Neon Design Technology, Inc. Retrieved 2011-07-21.
  11. Ring Team (3 December 2017). "Ring and other languages". ring-lang.
  12. "The Rust Reference" . Retrieved 16 November 2019.
  13. Lattner, Chris (2014-06-03). "Chris Lattner's Homepage". Chris Lattner. Retrieved 2014-06-03. The Swift language is the product of tireless effort from a team of language experts, documentation gurus, compiler optimization ninjas, and an incredibly important internal dogfooding group who provided feedback to help refine and battle-test ideas. Of course, it also greatly benefited from the experiences hard-won by many other languages in the field, drawing ideas from Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many others to list.
  14. "About Ruby" . Retrieved 15 February 2020.
  15. "Confreaks TV | Reasons behind Ruby - Ruby Conference 2008". Retrieved 2019-06-25.
  16. Shugo Maeda (17 December 2002). "The Ruby Language FAQ" . Retrieved 2 March 2014.
  17. Matsumoto, Yukihiro (13 February 2006). "Re: Ruby's lisp features" . Retrieved 15 February 2020.
  18. 1 2 3 4 5 6 "History of Ruby".
  19. "[FYI: historic] The decisive moment of the language name Ruby. (Re: [ANN] ruby 1.8.1)" (E-mail from Hiroshi Sugihara to ruby-talk).
  20. "The Ruby Language FAQ – 1.3 Why the name 'Ruby'?". Retrieved April 10, 2012.
  21. Yukihiro Matsumoto (June 11, 1999). "Re: the name of Ruby?". Ruby-Talk (Mailing list). Retrieved April 10, 2012.
  22. "More archeolinguistics: unearthing proto-Ruby". Archived from the original on 6 November 2015. Retrieved 2 May 2015.
  23. "[ruby-talk:00382] Re: history of ruby" . Retrieved 2 May 2015.
  24. "[ruby-list:124] TUTORIAL - ruby's features" . Retrieved 2 May 2015.
  25. "An Interview with the Creator of Ruby".
  26. Yukihiro Matsumoto (October 2000). "Programming Ruby: Forward" . Retrieved 5 March 2014.
  27. 1 2 "We retire Ruby 1.8.7" . Retrieved 2 May 2015.
  28. "IPA 独立行政法人 情報処理推進機構:プレス発表 プログラム言語RubyのJIS規格(JIS X 3017)制定について" . Retrieved 2 May 2015.
  29. "IPA 独立行政法人 情報処理推進機構:プレス発表 プログラム言語Ruby、国際規格として承認" . Retrieved 2 May 2015.
  30. "ISO/IEC 30170:2012" . Retrieved 2017-03-10.
  31. Web Development: Ruby on Rails. (2007-03-22). Retrieved on 2013-07-17.
  32. "Ruby 1.9.3 p0 is released". October 31, 2011. Retrieved February 20, 2013.
  33. "v1_9_3_0/NEWS". Ruby Subversion source repository. September 17, 2011. Retrieved February 20, 2013.
  34. Ruby 1.9: What to Expect. Retrieved on 2013-07-17.
  35. "Support for Ruby 1.9.3 has ended" . Retrieved 2 May 2015.
  36. Endoh, Yusuke. (2013-02-24) Ruby 2.0.0-p0 is released. Retrieved on 2013-07-17.
  37. Endoh, Yusuke. (2013-02-24) Ruby 2.0.0-p0 is released. Retrieved on 2013-07-17.
  38. usa (2016-02-24). "Support plans for Ruby 2.0.0 and Ruby 2.1". Retrieved 2017-04-18.
  39. "Ruby 2.1.0 is released". December 25, 2013. Retrieved December 26, 2013.
  40. "Semantic Versioning starting with Ruby 2.1.0". December 21, 2013. Retrieved December 27, 2013.
  41. "Support for Ruby 2.1 has ended" . Retrieved 4 April 2017.
  42. "Ruby 2.2.0 Released". December 25, 2014. Retrieved January 4, 2015.
  43. "ruby/NEWS at v2_2_0 · ruby/ruby · GitHub". GitHub. Retrieved 2 May 2015.
  44. "Support of Ruby 2.2 has ended" . Retrieved 29 Dec 2019.
  45. Gustavo Frederico Temple Pedrosa, Vitor de Lima, Leonardo Bianconi (2015). "Ruby 2.2.1 Released" . Retrieved 12 July 2016.CS1 maint: multiple names: authors list (link)
  46. Gustavo Frederico Temple Pedrosa, Vitor de Lima, Leonardo Bianconi (2015). "v2.2.1 ChangeLog" . Retrieved 12 July 2016.CS1 maint: multiple names: authors list (link)
  47. Gustavo Frederico Temple Pedrosa, Vitor de Lima, Leonardo Bianconi (2014). "Specifying non volatile registers for increase performance in ppc64" . Retrieved 12 July 2016.CS1 maint: multiple names: authors list (link)
  48. Gustavo Frederico Temple Pedrosa, Vitor de Lima, Leonardo Bianconi (2014). "Specifying MACRO for increase performance in ppc64" . Retrieved 12 July 2016.CS1 maint: multiple names: authors list (link)
  49. "Ruby 2.3.0 changes and features - Running with Ruby".
  50. "Ruby/NEWS at v.2_3_0 - ruby/ruby - Github". GitHub. Retrieved 25 December 2015.
  51. "Ruby 2.4.0 Released". Retrieved 2016-12-30.
  52. "Ruby 2.5.0 Released" . Retrieved 2018-05-02.
  53. "Ruby 2.6.0 Released". Ruby Programming Language. 2018-12-25. Retrieved 2018-12-25.
  54. "Ruby 2.7.0 Released". Ruby Programming Language. 2019-12-25. Retrieved 2019-12-25.
  55. "Ruby 3.0.0 Released". Ruby Programming Language. 2020-12-25. Retrieved 2020-12-25.
  56. "The Ruby Community's Christmas Releases".
  57. "A Patch in Time: Securing Ruby".
  58. "ruby-1.8.0 released!".
  59. "Plans for 1.8.7".
  60. "EOL for Ruby 1.8.7 and 1.9.2".
  61. "Ruby 1.9.3-p551 Released".
  62. "Ruby 1.9.0 Released".
  63. "Support for Ruby version 1.9.3 will end on February 23, 2015".
  64. "Support for Ruby 1.9.3 has ended".
  65. 1 2 3 "Ruby 2.0.0-p648 Released".
  66. "Ruby 2.0.0-p0 is released".
  67. "Ruby 2.1.10 Released".
  68. "Ruby 2.1.0 is released".
  69. "Support plans for Ruby 2.0.0 and Ruby 2.1".
  70. "Ruby 2.1.9 Released".
  71. "ReleaseEngineering - Ruby - Ruby Issue Tracking System".
  72. 1 2 "Support of Ruby 2.1 has ended".
  73. "Ruby 2.2.10 Released".
  74. "Ruby 2.2.0 Released".
  75. "Ruby 2.2.7 Released".
  76. "Ruby 2.3.8 Released".
  77. "Ruby 2.3.0 Released".
  78. 1 2 "Support of Ruby 2.2 has ended".
  79. "Ruby 2.4.10 Released". Ruby Programming Language. 2020-03-31. Retrieved 2020-04-01.
  80. "Ruby 2.4.0 Released".
  81. 1 2 "Support of Ruby 2.4 has ended".
  82. 1 2 3 "Ruby 2.5.9 Released". Ruby Programming Language. 2021-04-05. Retrieved 2021-04-05.
  83. "Ruby 2.5.0 Released".
  84. 1 2 3 "Ruby 2.6.7 Released". Ruby Programming Language. 2021-04-05. Retrieved 2021-04-05.
  85. "Ruby 2.6.0 Released".
  86. "Ruby 2.7.3 Released". Ruby Programming Language. 2021-04-05. Retrieved 2021-04-05.
  87. "Ruby 2.7.0 Released".
  88. "Ruby 3.0.1 Released". Ruby Programming Language. 2021-04-05. Retrieved 2021-04-05.
  89. "Ruby 3.0.0 Released".
  90. "The Ruby Programming Language" . Retrieved 2 May 2015.
  91. Google Tech Talks – Ruby 1.9 on YouTube
  92. 1 2 3 Bill Venners. "The Philosophy of Ruby" . Retrieved 2 May 2015.
  93. "Welcome to RUBYWEEKLYNEWS.ORG". 4 July 2017. Archived from the original on 4 July 2017.CS1 maint: bot: original URL status unknown (link)
  94. Bruce Stewart (29 November 2001). "An Interview with the Creator of Ruby - O'Reilly Media" . Retrieved 2 May 2015.
  95. Bill Venners. "Dynamic Productivity with Ruby" . Retrieved 2 May 2015.
  96. "Language Workbenches: The Killer-App for Domain Specific Languages?". Retrieved 2 May 2015.
  97. "Ruby – Add class methods at runtime".
  98. Bill Venners. "Blocks and Closures in Ruby" . Retrieved 2 May 2015.
  99. "Methods". Official Ruby FAQ.
  100. Britt, James. "Ruby 2.0.0 Standard Library Documentation" . Retrieved 2013-12-09.
  101. Green threads
  102. "The Ruby Language FAQ: How Does Ruby Stack Up Against...?" . Retrieved 2 May 2015.
  103. "[ruby-talk:01120] Re: The value of while..." In Ruby's syntax, statement is just a special case of an expression that cannot appear as an argument (e.g. multiple assignment).
  104. "[ruby-talk:02460] Re: Precedence question". statement [...] can not be part of expression unless grouped within parentheses.
  105. "GitHub - remove/virtual_module: Born to make your Ruby Code more than 3x faster. Hopefully".
  106. Peter Cooper (2010-05-18). "The Why, What, and How of Rubinius 1.0's Release".
  107. Maya Stodte (February 2000). "IBM developerWorks – Ruby: a new language". Archived from the original on August 18, 2000. Retrieved 3 March 2014.
  108. Yukihiro Matsumoto (August 2002). "lang-ruby-general: Re: question about Ruby initial development" . Retrieved 3 March 2014.
  109. Yukihiro Matsumoto (5 January 1999). "ruby-talk: Re: hah, check these errors" . Retrieved 3 March 2014.
  110. "Iron Ruby on Windows Phone 7".
  111. "The Ruby Toolbox" . Retrieved 2015-04-04.
  112. "We retire". 2013-08-08. Retrieved 2016-01-03.

Further reading