Ruby 1.9 brings a shorter way to define lambdas using the -> operator:

twice = -> (x) { 2 * x }
twice.call(5) # => 10

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more

This is equivalent to:

twice = lambda {|x| 2 * x }
twice.call(5) # => 10

Note that the syntax is subtly different from Coffeescript where you define function parameters before the arrow: (x) -> { 2 * x }.