search.rb

def answer?(str)
  filtered = str.split('').keep_if{|s| s.match(/[a-zA-Z0-9-]/)}

  if filtered && filtered.count == filtered.uniq.count
    return true
  end

  false
end

pp IO.readlines("./english_collocates.md", chomp: true).keep_if{|s| answer?(s)}.sort_by{|s| s.length}