0.rb

def make_awesome meth
  proc do |*args, &block|
    block ||= -> elem { elem.send *args }
    send meth, &block
  end
end

def patch_the_monkey
  %w[map select].each do |m|
    alias_method m * 2, m
    define_method m, make_awesome(m * 2)
  end
end

class Array
  patch_the_monkey
end

module Enumerable
  patch_the_monkey
end

p (1..10).map :to_s, 2
p [1,2,3].select :>, 1