Imperative `Hash.new` vs functional

count_colors.rb

# Task: Count how many users have each favorite color

User = Struct.new(:id, :favorite_color)

colors = [:red, :green, :blue, :hot_pink]

users = 10.times.map { |n| User.new(n, colors.sample) }

# The follow two example print the same result

## Imperative approach
counts = Hash.new(0)

users.each do |user|
  counts[user.favorite_color] += 1
end

p counts

## Functional approach
p Hash[
  users
    .group_by(&:favorite_color)
    .map { |color, users| [color, users.count] }
]