Except when it's your enemy: https://github.com/commercialhaskell/stack/issues/2884 see also http://tunes.org/~nef/logs/haskell/17.03.18 at 02:48:19 and following.

This conflation is stupid, prone to cause problems when multiple processes are involved, and needs to go away. Trying to hide the difference between buffering and tty mode from users just causes problems, because buffering is process local but the tty mode is shared between all processes using the tty.
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