Composição Ruby Proc

class Proc

  def compose(&blk)
    self.class.new { |*argv| blk.call(self.call(*argv)) }
  end

  alias :comp :compose
end

one_to_one = proc { |name| name + " trick" }.comp(&:upcase)

two_to_one = proc { |desc| desc.upcase }.compose { |name, age| "name: #{name} age: #{age}" }

puts one_to_one.call("dumb") 
puts two_to_one.call("person", 37) 

Os resultados acima:

$ DUMB TRICK
$ NAME: PERSON AGE: 37