Consider using newtypes for `Queue` and `TimeoutS`, for obvious reasons.
Also, use `Text` as an internal representation for `Queue`, as `String`
is just a list in disguise and thus quite slow in its cons-snoc semantic
(unlike `Text`, which efficiently represent textual data). `Text` also
supports UTF-16, which might be preferrable in some situations.

The use of DerivingStrategies makes it possible to print and render
queues in a "smart" way, for example:

  putStrLn $ show $ T.unpack $ _Queue (Queue "foo")
  putStrLn $ show (Queue "foo")

They both output "foo", without the intermediate `Queue` constructor one
would get by normal (stock) derivation.