Choosing a magic number between 0 and 9 I wrote a little script that asks the user to choose a number between the 0 and 9. Wile he/she is entering a choice, the program tells him/her if the number is too high and too low.

Nothing fancy, just a couple of while and ifs. It's very ugly and has imperative code with mixed responsibilities. I was wondering if there are some Ruby idioms that would make this code more readable and compact. I'm looking for some functions like in functional languages, or maybe there are special Ruby functions I'm not aware off. I don't want to define functions and classes for this simple program.

keepGoing = true
numberToGuess = rand(10)
firstRun = true
response = ''
while keepGoing
    if firstRun
        puts 'Find the magic number between O and 9'
        firstRun = false
    end
    proposedN = gets.chomp.to_i
    if proposedN == numberToGuess
        firstRun = true
        puts "You found the correct number : #{numberToGuess}"
        puts 'Another try ? (Y/N)'
        numberToGuess = rand(10)
        response = gets.chomp
        while response != 'N' and response != 'Y'
            puts 'Please fill in either Y or N'
            response = gets.chomp
        end
        response == 'N' ? keepGoing = false : keepGoing = true
        response = ''
    else
        if proposedN &gt; numberToGuess 
            puts 'Too high'
        else
            puts 'Too low' 
        end
    end
end
Well, you already identified the main issue with your code, and I concur: the imperative style. Also, note that this code should have two loops and you are doing it all in one, that's why you have to use flags all over the place. Since you asked for a functional solution, no while nor loop,  use recursion:

def guess_number(number_to_guess)
  guess = gets.to_i
  if guess == number_to_guess
    puts("You found the correct number: #{number_to_guess}")
  else
    puts(guess &gt; number_to_guess ? "Too high" : "Too low")
    guess_number(number_to_guess)
  end
end

def game
  puts('Find the magic number between O and 9')
  guess_number(rand(10))
  print('Another try? (Y/N): ')
  if gets.strip.downcase == "y"
    game
  end
end

game


If you want to validate the input, create a method def get(validation_regexp) and use it: get(/^\d+$/) and get(/^[yYnN]$/).