Mapping without the curly braces ;)

mapper.rb

class MethodChainer < BasicObject
  def initialize(obj, deep_chain = false)
    @obj = obj
    @deep_chain = deep_chain
  end
  
  def __
    @obj.map { |e| e }
  end

  def method_missing(name, *args)
    result = (@obj.map { |e| e.send(name, *args) })
    return result unless @deep_chain
    result.__
  end
end

module Enumerable
  def _
    map._
  end
  
  def __
    map.__
  end
end

class Enumerator
  def _
    MethodChainer.new(self)
  end
  
  def __
    MethodChainer.new(self, deep_chain: true)
  end
end

a = ['Yeah',2,'Hello WoRlD']

a.map._.to_s # => ["Yeah", "2", "Hello WoRlD"]
a._.to_s     # => ["Yeah", "2", "Hello WoRlD"]

a.map.__.to_s.downcase.reverse.__ # => ["haey", "2", "dlrow olleh"]
a.__.to_s.downcase.reverse.__     # => ["haey", "2", "dlrow olleh"]