ReverseLinkedList.rb

require 'ostruct'

o = OpenStruct.new(value: 1, tail: OpenStruct.new(value: 2, tail: OpenStruct.new(value: 3, tail: nil)))

def reverse(list, rest = nil)
  result = cons(list.value, rest)
  if list.tail.nil?
    result
  else
    reverse(list.tail, result)
  end
end

def cons(value, rest)
  OpenStruct.new(value: value, tail: rest)
end

puts reverse(o)