A little comparison between groovy and ruby nested hashes with defaults

hash_play_time.groovy

class Person {
  public name
  public gender
  public age

  public Person(name, gender, age) {
    this.name = name
    this.gender = gender
    this.age = age
  }

  def decade() {
    return "${age - (age % 10)}+"
  }
}

family = [
  new Person("Sofia", "female", 1),
  new Person("Aiko", "female", 1),
  new Person("Vanja", "male", 37),
  new Person("Branka", "female", 38),
  new Person("Fuma", "female", 83),
  new Person("Ranko", "male", 64),
  new Person("Mira", "female", 64),
  new Person("Tomo", "male", 67),
  new Person("Zorica", "female", 66),
  new Person("Greta", "female", 14),
  new Person("Gael", "male", 21),
  new Person("Vigo", "male", 11),
  new Person("Mitchell", "male", 43),
  new Person("Michel", "female", 22)
]

by_gender_and_decade = [:].withDefault() { [:].withDefault() {0} }

family.each { person ->
  by_gender_and_decade[person.gender][person.decade()] += 1
}

def prettify(hash) {
  return hash.collect { key, value -> "${key} / ${value}" }.join(", ")
}

println "Family members by gender and age group:"
println "female: ${prettify(by_gender_and_decade["female"])}"
println "male: ${prettify(by_gender_and_decade["male"])}"

hash_play_time.rb

Person = Struct.new(:name, :gender, :age) {
  def decade
    "#{age - (age % 10)}+"
  end
}

family = [
  Person.new("Sofia", :female, 1),
  Person.new("Aiko", :female, 1),
  Person.new("Vanja", :male, 37),
  Person.new("Branka", :female, 38),
  Person.new("Fuma", :female, 83),
  Person.new("Ranko", :male, 64),
  Person.new("Mira", :female, 64),
  Person.new("Tomo", :male, 67),
  Person.new("Zorica", :female, 66),
  Person.new("Greta", :female, 14),
  Person.new("Gael", :male, 21),
  Person.new("Vigo", :male, 11),
  Person.new("Mitchell", :male, 43),
  Person.new("Michel", :female, 22)
]

by_gender_and_decade = Hash.new { |hash, key| hash[key] = Hash.new(0) }

family.each do |person|
  by_gender_and_decade[person.gender][person.decade] += 1
end

def prettify(hash)
  hash.collect { |key, value| "#{key} / #{value}" }.join(", ")
end

puts "Family members by gender and age group:"
puts "female: #{prettify(by_gender_and_decade[:female])}"
puts "male: #{prettify(by_gender_and_decade[:male])}"