What's the difference between functional and imperative? Find out

imperative_vs_functional.rb

puts "Hello. Welcome to the Functional World!"

#
# This is how to do it imperative style (aka: Stupid Java programmer)
# 
array = [1,2,3,4]
new_array = []
array.each do |n|
  if n % 2 == 0
    new_array.push n
  end
end


#
# Alterative syntax that a mint Java-programmer-turned-Ruby-programmer probably would do
#
array = [1,2,3,4]
new_array = []
array.each do |n|
  new_array.push n if n % 2 == 0
end


#
# This is another way to do it imperative style (smarter Ruby programmer)
# 
array = [1,2,3,4]
new_array = array.select do |n|
  if n.even?
    true
  else
    false
  end
end


#
# The truly functional way (smart Rubyist. Aka Functional Nirvana). Notice the 
# output variable's name has been smartly renamed
#
even_numbers = [1,2,3,4].select { |n| n.even? }