gistfile1.rb

module PartiallyApplicable
  def apply_partially(new_name, old_name, *fixed_args)
    define_method(new_name) do |*args|
      self.send(old_name, *(fixed_args + args))
    end
  end
end

class MyClass
  extend PartiallyApplicable

  def plus(x, y)
    x + y
  end
  apply_partially :plus1, :plus, 1
end

raise unless MyClass.new.plus(1, 2) == MyClass.new.plus1(2)