= Ruby Standard Library

The Ruby Standard Library is a vast collection of classes and modules that you
can require in your code for additional features.

Below is an overview of libraries and extensions followed by a brief
description.

== Libraries

MakeMakefile:: Module used to generate a Makefile for C extensions
RbConfig:: Information of your configure and build of Ruby
Gem:: Package management framework for Ruby

== Extensions

Coverage:: Provides coverage measurement for Ruby
Monitor:: Provides an object or module to use safely by more than one thread
objspace:: Extends ObjectSpace module to add methods for internal statistics
PTY:: Creates and manages pseudo terminals
Ripper:: Provides an interface for parsing Ruby programs into S-expressions
Socket:: Access underlying OS socket implementations

= Default gems

* default gems are shipped with Ruby releases and also available as rubygems.
* default gems are not uninstallable from Ruby installation.
* default gems can be updated used by rubygems.
    * e.g. `gem update json`
* default gems can be used with bundler environment like `unbundled_env`.
* default gems can be used any version on Gemfile.
    * e.g. `gem "json", ">= 2.6"`

== Libraries

Abbrev:: Calculates a set of unique abbreviations for a given set of strings
Base64:: Support for encoding and decoding binary data using a Base64 representation
Benchmark:: Provides methods to measure and report the time used to execute code
Bundler:: Manage your Ruby application's gem dependencies
CGI:: Support for the Common Gateway Interface protocol
CSV:: Provides an interface to read and write CSV files and data
Delegator:: Provides three abilities to delegate method calls to an object
DidYouMean:: "Did you mean?" experience in Ruby
DRb:: Distributed object system for Ruby
English:: Provides references to special global variables with less cryptic names
ERB:: An easy to use but powerful templating system for Ruby
ErrorHighlight:: Highlight error location in your code
FileUtils:: Several file utility methods for copying, moving, removing, etc
Find:: This module supports top-down traversal of a set of file paths
Forwardable:: Provides delegation of specified methods to a designated object
GetoptLong:: Parse command line options similar to the GNU C getopt_long()
IPAddr:: Provides methods to manipulate IPv4 and IPv6 IP addresses
IRB:: Interactive Ruby command-line tool for REPL (Read Eval Print Loop)
OptionParser:: Ruby-oriented class for command-line option analysis
Logger:: Provides a simple logging utility for outputting messages
Mutex_m:: Mixin to extend objects to be handled like a Mutex
Net::HTTP:: HTTP client api for Ruby
Observable:: Provides a mechanism for publish/subscribe pattern in Ruby
Open3:: Provides access to stdin, stdout and stderr when running other programs
OpenStruct:: Class to build custom data structures, similar to a Hash
OpenURI:: An easy-to-use wrapper for Net::HTTP, Net::HTTPS and Net::FTP
PP:: Provides a PrettyPrinter for Ruby objects
PrettyPrinter:: Implements a pretty printing algorithm for readable structure
PStore:: Implements a file based persistence mechanism based on a Hash
Readline:: Wrapper for Readline extencion and Reline
Reline:: GNU Readline and Editline by pure Ruby implementation.
Resolv::  Thread-aware DNS resolver library in Ruby
resolv-replace.rb:: Replace Socket DNS with Resolv
RDoc:: Produces HTML and command-line documentation for Ruby
Rinda:: The Linda distributed computing paradigm in Ruby
SecureRandom:: Interface for secure random number generator
Set:: Provides a class to deal with collections of unordered, unique values
Shellwords:: Manipulates strings with word parsing rules of UNIX Bourne shell
Singleton:: Implementation of the Singleton pattern for Ruby
Tempfile:: A utility class for managing temporary files
Time:: Extends the Time class with methods for parsing and conversion
Timeout:: Auto-terminate potentially long-running operations in Ruby
tmpdir.rb:: Extends the Dir class to manage the OS temporary file path
TSort:: Topological sorting using Tarjan's algorithm
un.rb:: Utilities to replace common UNIX commands
URI:: A Ruby module providing support for Uniform Resource Identifiers
YAML:: Ruby client library for the Psych YAML implementation
WeakRef:: Allows a referenced object to be garbage-collected

== Extensions

BigDecimal:: Provides arbitrary-precision floating point decimal arithmetic
Date:: A subclass of Object includes Comparable module for handling dates
DateTime:: Subclass of Date to handling dates, hours, minutes, seconds, offsets
Digest:: Provides a framework for message digest libraries
Etc:: Provides access to information typically stored in UNIX /etc directory
Fcntl:: Loads constants defined in the OS fcntl.h C header file
Fiddle:: A libffi wrapper for Ruby
IO:: Extensions for Ruby IO class, including #wait, #nonblock and ::console
JSON:: Implements Javascript Object Notation for Ruby
NKF:: Ruby extension for Network Kanji Filter
OpenSSL:: Provides SSL, TLS and general purpose cryptography for Ruby
Pathname:: Representation of the name of a file or directory on the filesystem
Psych:: A YAML parser and emitter for Ruby
Racc:: A LALR(1) parser generator written in Ruby.
StringIO:: Pseudo I/O on String objects
StringScanner:: Provides lexical scanning operations on a String
Syslog:: Ruby interface for the POSIX system logging facility
WIN32OLE:: Provides an interface for OLE Automation in Ruby
Zlib:: Ruby interface for the zlib compression/decompression library

= Bundled gems

* bundled gems are shipped with Ruby releases and also available as rubygems.
* bundled gems are same as normal gems like `rails`, `rack`.
    * They are only bundled with Ruby releases.
    * They can be uninstallable from Ruby installation.
    * They are needed to declare in Gemfile when use with bundler.

== Libraries

MiniTest:: A test suite with TDD, BDD, mocking and benchmarking
PowerAssert:: Power Assert for Ruby.
Rake:: Ruby build program with capabilities similar to make
Test::Unit:: A compatibility layer for MiniTest
REXML:: An XML toolkit for Ruby
RSS:: Family of libraries that support various formats of XML "feeds"
Net::FTP:: Support for the File Transfer Protocol
Net::IMAP:: Ruby client api for Internet Message Access Protocol
Net::POP3:: Ruby client library for POP3
Net::SMTP:: Simple Mail Transfer Protocol client library for Ruby
Matrix:: Represents a mathematical matrix.
Prime:: Prime numbers and factorization library
RBS:: RBS is a language to describe the structure of Ruby programs
TypeProf:: A type analysis tool for Ruby code based on abstract interpretation
DEBUGGER__:: Debugging functionality for Ruby
