hangman using ruby fibers

fiber_hangman.rb

#!/usr/bin/env ruby
require 'fiber'
require 'set'

def state full_word, revealed
  all_letters = full_word.split('') - [' ']
  hidden = all_letters.to_set - revealed
  hidden.inject(full_word) {|acc, e| acc.gsub e, '_' }
end

game = Fiber.new do |fiber, word|
  all_letters = word.split('').to_set - [' ']
  guessed_letters = Set.new
  loop do
    puts "--> #{state word, guessed_letters}"
    input = Fiber.yield
    if input.size > 1
      if input == word
        break
      else
        fiber.resume :incorrect
      end
    elsif input.size == 1
      if all_letters.member? input
        guessed_letters << input
        if guessed_letters == all_letters
          break
        else
          fiber.resume :correct
        end
      else
        fiber.resume :incorrect
      end
    end
  end
  fiber.resume :completed
end

result = Fiber.new do
  loop do
    case Fiber.yield
    when :incorrect
      puts "Guess incorrect"
    when :correct
      puts "Guess is correct"
    when :completed
      puts "finished puzzle"
    else
      puts "unknown response"
    end
  end
end

result.resume
game.resume result, "testing"

loop do
  print '> '
  if game.alive?
    game.resume gets.chomp
  else
    puts "Finished."
    break
  end
end