Look and say sequence (Ruby)

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This is a simple Ruby program to generate look-and-say sequences such as the Conway sequence. 

<<look_and_say_sequence.rb>>=
require "generator"
def look_and_say(seed, len)
  Generator.new do |g|
    last_value = seed.to_s
    g.yield last_value
    2.upto(len) do
      next_value = ""
      while last_value.length > 0
        match = /#{last_value[0,1]}+/.match(last_value)[0]
        next_value << match.length.to_s + last_value[0,1]
        last_value = last_value[match.length..last_value.length]       
      end
      last_value = next_value
      g.yield next_value
    end 
  end
end

print conway sequence

We test the look and say sequence generator by printing the first 10 numbers of the Conway sequence to the console: 

<<print conway sequence>>=
def test_look_and_say()
  conway = look_and_say(3,10)
  puts conway.to_a
end
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