module Data.InOrOut where


-- | This wrapper is useful for tagging another type
--   as being of either an In variety or an Out variety.
--
--   For example, incoming messages can be tagged as In
--   and outgoing messages could be tagged as Out.
--
--   Another use case is tagging handles so that
--   you only output to Out Handle and only input
--   from In Handle.
data InOrOut a = In a | Out a