>>10
headとかdrop 1とか使うよりパターンマッチの方が楽だぜ

groupEmptyLine :: [String] -> [String]
groupEmptyLine ls = case ls of
  [] -> []
  []:[]:rest -> groupEmptyLine ([]:rest)
  line:rest -> line : groupEmptyLine rest

createLineNumber :: Int -> [String] -> [String]
createLineNumber n ls = case ls of
  [] -> []
  []:rest -> [] : createLineNumber n rest
  line:rest -> (fillSpace 6 n ++ ":" ++ line) : createLineNumber (n + 1) rest