Ruby script to list prime numbers.

prime_number_list.rb

#! /usr/local/bin/ruby
# coding: utf-8
# --------------------------------------
#   Prime numbers list
# --------------------------------------

class PrimeNumber
  def exec(nums)
    (1..nums).each do |n|
      puts "#{n}: #{is_prime(n) ? 'PRIME' : '----- '}"
    end
  end

private

  def is_prime(n)
    res = (2..Math.sqrt(n)).any? { |i| n % i == 0 }
    return res || n == 1 ? false : true
  end
end

PrimeNumber.new.exec(99) if __FILE__ == $0