#!/usr/bin/env ruby

WORDS = File.open("/usr/share/dict/words", &:read).lines.map do |word|
  word.strip.downcase
end.freeze

def word?(word)
  WORDS.include? word.downcase
end

def permute(letters, prefix: "", &cb)
  1.upto letters.size do
    cur_prefix = prefix + letters.first
    test_set = letters[1..]

    if letters.size > 2
      permute test_set, prefix: cur_prefix, &cb
    else
      word = cur_prefix + test_set.join

      if word? word
        yield word
      end
    end

    letters = letters.rotate
  end
end

permute %w[u h s e t l] do |word|
  puts word
end