An example #filter_map in Ruby

filter_map.rb

module Enumerable
  def filter_map filter, mapper
    each_with_object([]) do |item, result|
      result << mapper.call(item) if filter.call(item)
    end
  end
end

[1, 2, 3, 4].filter_map :even?.to_proc, :to_s.to_proc
#=> ["2", "4"]