Ruby

TL;DR

En resumen: Ruby está diseñado para la felicidad del desarrollador - expresivo, elegante y productivo.

Fortalezas principales:

• Sintaxis hermosa y legible
• Todo es un objeto
• Framework Rails para desarrollo web rápido
• Comunidad vibrante y rico ecosistema de gemas

Philosophy

Ruby sigue el principio de menor sorpresa:

• Optimizado para la felicidad del desarrollador - Matz diseñó Ruby para que sea divertido
• Todo es un objeto - Incluso los números y nil tienen métodos
• Duck typing - Si camina como pato, es un pato
• Convención sobre configuración - Valores predeterminados sensatos, menos boilerplate

Ruby valora la expresividad sobre el rendimiento. Es un lenguaje donde escribes lo que quieres decir.

Quick Start

Install

# macOS
brew install ruby

# Linux - use version manager (recommended)
curl -fsSL https://github.com/rbenv/rbenv-installer/raw/HEAD/bin/rbenv-installer | bash
rbenv install 3.4.8
rbenv global 3.4.8

Verify (latest: 3.4.8)

ruby --version  # ruby 3.4.8

First Program

Crea hello.rb:

puts "Hello, World!"

ruby hello.rb

Interactive Ruby (IRB)

irb
>> 2 + 2
=> 4
>> "hello".upcase
=> "HELLO"

Language Essentials

Variables & Types

# Variables (no type declarations)
name = "Alice"
age = 25
price = 19.99
active = true

# Symbols (immutable identifiers)
status = :pending

# Arrays
numbers = [1, 2, 3]
mixed = [1, "two", :three]

# Hashes (dictionaries)
user = { name: "Alice", age: 25 }
user[:name]  # "Alice"

Control Flow

# if-else
if age >= 18
  puts "Adult"
elsif age >= 13
  puts "Teen"
else
  puts "Child"
end

# One-liner
puts "Adult" if age >= 18

# unless (opposite of if)
puts "Minor" unless age >= 18

# case (pattern matching)
case status
when :pending
  "Waiting"
when :active, :running
  "In progress"
else
  "Unknown"
end

Iterators & Blocks

# Blocks are everywhere
5.times { puts "Hello" }

# each
[1, 2, 3].each { |n| puts n }

# map
doubled = [1, 2, 3].map { |n| n * 2 }  # [2, 4, 6]

# select (filter)
evens = [1, 2, 3, 4].select { |n| n.even? }  # [2, 4]

# Multi-line block
numbers.each do |n|
  puts n * 2
end

Methods

# Method definition
def greet(name)
  "Hello, #{name}!"  # Implicit return
end

# Default parameters
def greet(name, greeting = "Hello")
  "#{greeting}, #{name}!"
end

# Keyword arguments
def create_user(name:, age:, admin: false)
  { name: name, age: age, admin: admin }
end

create_user(name: "Alice", age: 25)

Classes

class User
  attr_accessor :name, :age  # Getters and setters

  def initialize(name, age)
    @name = name  # Instance variable
    @age = age
  end

  def adult?
    @age >= 18
  end
end

user = User.new("Alice", 25)
user.name       # "Alice"
user.adult?     # true

Gotchas

nil es falsy, pero 0 y "" son truthy

if nil
  # won't run
end

if 0
  puts "0 is truthy!"  # Will print!
end

if ""
  puts "empty string is truthy!"  # Will print!
end

Symbols vs Strings

# Symbols are immutable and memory-efficient
:name.object_id == :name.object_id  # true

# Strings are mutable
"name".object_id == "name".object_id  # false

# Use symbols for hash keys
user = { name: "Alice" }  # Symbol key
user[:name]               # Access with symbol

Retorno implícito

def add(a, b)
  a + b  # Last expression is returned
end

# Explicit return only when needed
def early_exit(n)
  return "negative" if n < 0
  n * 2
end

Convenciones de nombres de métodos

# ? for predicates (return boolean)
"hello".empty?    # false
[1, 2].include?(1)  # true

# ! for dangerous/mutating methods
str = "hello"
str.upcase   # Returns "HELLO", str unchanged
str.upcase!  # Modifies str in place

When to Choose

Ideal para:

• Aplicaciones web (Ruby on Rails)
• Prototipado rápido
• Scripting y automatización
• Startups que necesitan desarrollo rápido

No ideal para:

• Aplicaciones críticas en rendimiento
• Desarrollo móvil
• Ciencia de datos (usar Python)

Comparación:

Aspecto	Ruby	Python	JavaScript
Framework web	Rails	Django	Express
Sintaxis	Elegante	Limpia	Flexible
Velocidad	Lento	Medio	Medio
Caso de uso	Web	General	Full-stack

Next Steps

• Ruby Documentation
• Ruby in 20 Minutes
• Ruby on Rails
• RubyGems

Ecosystem

Package Management

gem install rails       # Install a gem
gem list                # List installed gems
bundle init             # Create Gemfile
bundle install          # Install dependencies

Popular Gems

• Web: Rails, Sinatra, Hanami
• Testing: RSpec, Minitest
• Database: ActiveRecord, Sequel
• Background Jobs: Sidekiq, Resque