Permute name

permute_name.rb

require 'set'

last = (ARGV.shift || fail('<int> Permute of last n chars must be set')).to_i
seed = ARGV

fail 'At least one seed must be provided' if seed.empty?

def say(name)
  puts name
 `say #{name}`
  name
end

def permutations(name, n)
  head  = name[0..-(n - 1)]
  tails = name[-n..-1].chars.permutation.map(&:join)
  tails.each { |tail| yield(head + tail) }
end

names = seed
found = Set.new
names.each do |name|
  found << say(name)
  permutations(name, last) do |permutation|
    found << say(permutation) unless found.include?(permutation)
  end
end